Method and apparatus for transmitting and receiving channel state information-reference signal (CSI-RS)

ABSTRACT

Disclosed is a method for transmitting and receiving a channel state information (CSI)-reference signal (RS) in a wireless communication system. 
     Specifically, the method performed by a base station may include: configuring control information indicating that an antenna port for all CSI-RS resources included in a CSI-RS resource set is same, wherein the CSI-RS resource set is used for tracking at least one of a time or a frequency; transmitting the configured control information to a user equipment (UE); and transmitting the CSI-RS to the UE through all the CSI-RS resources. 
     In doing so, the UE is capable of performing time/frequency tracking more precisely.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/126,462, filed Sep. 10, 2018, which is a continuation of and claimspriority under 35 U.S.C. § 120 to International Application No.PCT/KR2018/008296, filed on Jul. 23, 2018, which claims the benefit ofU.S. Provisional Application No. 62/535,243 filed on Jul. 21, 2017, U.S.Provisional Application No. 62/541,115 filed on Aug. 4, 2017 and U.S.Provisional Application No. 62/554,586 filed on Sep. 6, 2017, thecontents of which are all hereby incorporated by reference herein intheir entirety.

TECHNICAL FIELD

The present disclosure relates to a wireless communication system and,more particularly, to a method for transmitting and receiving a channelstate information (CSI)-reference signal (RS) and an apparatussupporting the same.

BACKGROUND ART

Mobile communication systems have been generally developed to providevoice services while guaranteeing user mobility. Such mobilecommunication systems have gradually expanded their coverage from voiceservices through data services up to high-speed data services. However,as current mobile communication systems suffer resource shortages andusers demand even higher-speed services, development of more advancedmobile communication systems is needed.

The requirements of the next-generation mobile communication system mayinclude supporting huge data traffic, a remarkable increase in thetransfer rate of each user, the accommodation of a significantlyincreased number of connection devices, very low end-to-end latency, andhigh energy efficiency. To this end, various techniques, such as smallcell enhancement, dual connectivity, massive multiple input multipleoutput (MIMO), in-band full duplex, non-orthogonal multiple access(NOMA), supporting super-wide band, and device networking, have beenresearched.

DISCLOSURE Technical Problem

The present disclosure is to provide a method of designing a referencesignal (RS) (e.g., TRS) to be used for time/frequency tracking.

The present disclosure proposes a method of explicitly or implicitlyproviding configuration of a TRS.

It is to be understood that technical objects to be achieved by thepresent invention are not limited to the aforementioned technical objectand other technical objects which are not mentioned herein will beapparent from the following description to one of ordinary skill in theart to which the present invention pertains.

Technical Solution

The present disclosure provides a method of transmitting and receiving acontrol state information (CSI)-reference signal (RS) in a wirelesscommunication system.

Specifically, a method performed by a base station includes: configuringcontrol information indicating that an antenna port for all CSI-RSresources included in a CSI-RS resource set is same, wherein the CSI-RSresource set is used for tracking at least one of a time or a frequency;transmitting the configured control information to a user equipment(UE); and transmitting the CSI-RS to the UE through all the CSI-RSresources.

In the present disclosure, the antenna port may be 1-port

In the present disclosure, the UE may be a UE in a radio resourcecontrol (RRC) connected state.

In the present disclosure, the CSI-RS may be a periodic CSI-RS.

In the present disclosure, all the CSI-RS resources may be configuredwith a same periodicity.

In the present disclosure, all the CSI-RS resources may be configured ina single slot or multiple slots.

In the present disclosure, the multiple slots may be consecutive slots.

In the present disclosure, symbol locations of all the CSI-RS resourcesmay be different when all the CSI-RS resources are configured in thesingle slot.

In the present disclosure, code division multiplexing (CDM) may not beapplied to all the CSI-RS resources.

In the present disclosure, a frequency domain density of each of theCSI-RS resources may be greater than 1.

In the present disclosure, the CSI-RS resource set may not be configuredboth for the tracking and for beam management.

In the present disclosure, a CSI-RS resource used for the tracking maybe quasi co-located (QCL) with a CSI-RS resource used for CSIacquisition, a CSI-RS resource used for beam management, or an SS/PBCHblock (SSB).

In the present disclosure, a time domain measurement restriction for theCSI-RS may be set to “OFF”.

In the present disclosure, linkage between the CSI-RS resource set and areport setting may not be set.

In the present disclosure, linkage between the CSI-RS resource set and aspecific report setting may be set.

In the present disclosure, the specific report setting may be a nullreporting setting.

In the present disclosure, the method may further include receivinginformation related to a density of a time domain of the CSI-RS from theUE.

In the present disclosure, the time domain may be a single slot orconsecutive slots.

In addition, in the present disclosure, a method for receiving a channelstate information (CSI)-reference signal (RS) by a user equipment (UE)in a wireless communication system may include: receiving, from a basestation, control information indicating that an antenna port for allCSI-RS resources included in a CSI-RS resource set is same, wherein theCSI-RS resource set is used for tracking at least one of a time or afrequency; receiving, from the base station, the CSI-RS through all theCSI-resources; and tracking at least one of a time or a frequency basedon the received CSI-RS.

In addition, in the present disclosure, a base station which transmits achannel state information (CSI)-reference signal (RS) in a wirelesscommunication system and includes: a radio frequency (RF) moduleconfigured to transmit and receive a wireless signal; and a processorfunctionally connected to the RF module and configured to: configurecontrol information indicating that an antenna port for all CSI-RSresources included in a CSI-RS resource set is same, wherein the CSI-RSresource set is used for tracking at least one of a time or a frequency;transmit the configured control information to a user equipment (UE);and transmit the CSI-RS to the UE through all the CSI-RS resources.

Advantageous Effects

The present disclosure newly defines a tracking reference signal (TRS)so as to more precisely perform time/frequency tracking of a userequipment (UE).

It will be appreciated by those skilled in the art that the effects thatcan be achieved with the present invention are not limited to what hasbeen described above and other advantages of the present invention willbe clearly understood from the following detailed description taken inconjunction with the accompanying drawings.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included herein as a part of adescription in order to help understanding of the present disclosure,provide embodiments of the present disclosure, and describe thetechnical features of the present disclosure with the description below.

FIG. 1 is a diagram illustrating an example of an overall structure of anew radio (NR) system to which a method proposed by the presentdisclosure may be implemented.

FIG. 2 illustrates a relationship between a uplink (UL) frame and adownlink (DL) frame in a wireless communication system to which a methodproposed by the present disclosure may be implemented.

FIG. 3 illustrates an example of a resource grid supported in a wirelesscommunication system to which a method proposed by the presentdisclosure may be implemented.

FIG. 4 is a diagram illustrating an example of a self-contained subframestructure in a wireless communication system to which the presentdisclosure may be implemented.

FIG. 5 is an example of a transceiver unit model in a wirelesscommunication system to which the present disclosure may be implemented.

FIG. 6 is a flowchart illustrating an example of a control stateinformation (CSI)-related procedure.

FIG. 7 is a conceptual diagram illustrating an example of a beam-relatedmeasurement model.

FIG. 8 is a diagram illustrating a transmission (Tx) beam regarding adownlink (DL) beam management (BM) procedure.

FIG. 9 is a flowchart illustrating an example of the DL BM procedureusing a synchronization signal block (SSB).

FIG. 10 is a diagram illustrating an example of a DL BM procedure usinga CSI-RS.

FIG. 11 is a flowchart illustrating an example of a reception (Rx) beamdetermination procedure of a UE.

FIG. 12 is a flowchart illustrating an example of a Tx beamdetermination procedure of a base station.

FIG. 13 is a diagram illustrating an example of resource allocationrelated to operation of FIG. 10 in time and frequency domains.

FIG. 14 is a diagram illustrating an example of a UL BM procedure usingan SRS.

FIG. 15 is a flowchart illustrating a UL BM procedure using a soundingreference symbol (SRS).

FIG. 16 shows an example of information payload of a physical uplinkshared channel (PUSCH)-based CSI reporting.

FIG. 17 shows an example of information payload of a short physicaluplink control channel (PUCCH)-based CSI reporting.

FIG. 18 shows an example of information payload of a long PUCCH-basedCSI reporting.

FIG. 19 is a flowchart illustrating an example of a beam failurerecovery (BFR) procedure.

FIG. 20 is a flowchart illustrating operation of a base station fortime/frequency tracking, which is proposed in the present disclosure.

FIG. 21 is a flowchart illustrating time/frequency tracking operation ofa UE which is proposed in the present disclosure.

FIG. 22 is a block diagram of a wireless communication device to whichmethods proposed in the present disclosure may be applied.

FIG. 23 is a block diagram of a communication device according to anembodiment of the present disclosure.

FIG. 24 is a diagram illustrating an example of an RF module of awireless communication apparatus to which the method proposed in thepresent disclosure may be applied.

FIG. 25 is a diagram illustrating another example of an radio frequency(RF) module of a wireless communication apparatus to which the methodproposed in the present disclosure may be applied.

MODE FOR INVENTION

Some embodiments of the present disclosure are described in detail withreference to the accompanying drawings. A detailed description to bedisclosed along with the accompanying drawings is intended to describesome exemplary embodiments of the present disclosure and is not intendedto describe a sole embodiment of the present disclosure. The followingdetailed description includes more details in order to provide fullunderstanding of the present disclosure. However, those skilled in theart will understand that the present disclosure may be implementedwithout such more details.

In some cases, in order to avoid making the concept of the presentdisclosure vague, known structures and devices are omitted or may beshown in a block diagram form based on the core functions of eachstructure and device.

In the present disclosure, a base station has the meaning of a terminalnode of a network over which the base station directly communicates witha terminal. In this document, a specific operation that is described tobe performed by a base station may be performed by an upper node of thebase station according to circumstances. That is, it is evident that ina network including a plurality of network nodes including a basestation, various operations performed for communication with a terminalmay be performed by the base station or other network nodes other thanthe base station. The base station (BS) may be substituted with anotherterm, such as a fixed station, a Node B, an eNB (evolved-NodeB), a basetransceiver system (BTS), or an access point (AP). Furthermore, theterminal may be fixed or may have mobility and may be substituted withanother term, such as user equipment (UE), a mobile station (MS), a userterminal (UT), a mobile subscriber station (MSS), a subscriber station(SS), an advanced mobile station (AMS), a wireless terminal (WT), amachine-type communication (MTC) device, a machine-to-Machine (M2M)device, or a device-to-device (D2D) device.

Hereinafter, downlink (DL) means communication from a base station toUE, and uplink (UL) means communication from UE to a base station. InDL, a transmitter may be part of a base station, and a receiver may bepart of UE. In UL, a transmitter may be part of UE, and a receiver maybe part of a base station.

Specific terms used in the following description have been provided tohelp understanding of the present disclosure, and the use of suchspecific terms may be changed in various forms without departing fromthe technical sprit of the present disclosure.

The following technologies may be used in a variety of wirelesscommunication systems, such as code division multiple access (CDMA),frequency division multiple access (FDMA), time division multiple access(TDMA), orthogonal frequency division multiple access (OFDMA), singlecarrier frequency division multiple access (SC-FDMA), and non-orthogonalmultiple access (NOMA). CDMA may be implemented using a radiotechnology, such as universal terrestrial radio access (UTRA) orCDMA2000. TDMA may be implemented using a radio technology, such asglobal system for mobile communications (GSM)/general packet radioservice (GPRS)/enhanced data rates for GSM evolution (EDGE). OFDMA maybe implemented using a radio technology, such as Institute of electricaland electronics engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX),IEEE 802.20, or evolved UTRA (E-UTRA). UTRA is part of a universalmobile telecommunications system (UMTS). 3rd generation partnershipproject (3GPP) Long term evolution (LTE) is part of an evolved UMTS(E-UMTS) using evolved UMTS terrestrial radio access (E-UTRA), and itadopts OFDMA in downlink and adopts SC-FDMA in uplink. LTE-advanced(LTE-A) is the evolution of 3GPP LTE.

Embodiments of the present disclosure may be supported by the standarddocuments disclosed in at least one of IEEE 802, 3GPP, and 3GPP2, thatis, radio access systems. That is, steps or portions that belong to theembodiments of the present disclosure and that are not described inorder to clearly expose the technical spirit of the present disclosuremay be supported by the documents. Furthermore, all terms disclosed inthis document may be described by the standard documents.

In order to more clarify a description, 3GPP LTE/LTE-A is chieflydescribed, but the technical characteristics of the present disclosureare not limited thereto.

Definition of Terms

eLTE eNB: An eLTE eNB is an evolution of an eNB that supports aconnection for an EPC and an NGC.

gNB: A node for supporting NR in addition to a connection with an NGC

New RAN: A radio access network that supports NR or E-UTRA or interactswith an NGC

Network slice: A network slice is a network defined by an operator so asto provide a solution optimized for a specific market scenario thatrequires a specific requirement together with an inter-terminal range.

Network function: A network function is a logical node in a networkinfra that has a well-defined external interface and a well-definedfunctional operation.

NG-C: A control plane interface used for NG2 reference point between newRAN and an NGC

NG-U: A user plane interface used for NG3 reference point between newRAN and an NGC

Non-standalone NR: A deployment configuration in which a gNB requires anLTE eNB as an anchor for a control plane connection to an EPC orrequires an eLTE eNB as an anchor for a control plane connection to anNGC

Non-standalone E-UTRA: A deployment configuration an eLTE eNB requires agNB as an anchor for a control plane connection to an NGC.

User plane gateway: A terminal point of NG-U interface

General System

FIG. 1 is a diagram illustrating an example of an overall structure of anew radio (NR) system to which a method proposed by the presentdisclosure may be implemented.

Referring to FIG. 1, an NG-RAN is composed of gNBs that provide an NG-RAuser plane (new AS sublayer/PDCP/RLC/MAC/PHY) and a control plane (RRC)protocol terminal for a UE (User Equipment).

The gNBs are connected to each other via an Xn interface.

The gNBs are also connected to an NGC via an NG interface.

More specifically, the gNBs are connected to a Access and MobilityManagement Function (AMF) via an N2 interface and a User Plane Function(UPF) via an N3 interface.

NR (New Rat) Numerology and Frame Structure

In the NR system, multiple numerologies may be supported. Thenumerologies may be defined by subcarrier spacing and a CP (CyclicPrefix) overhead. Spacing between the plurality of subcarriers may bederived by scaling basic subcarrier spacing into an integer N or μ. Inaddition, although a very low subcarrier spacing is assumed not to beused at a very high subcarrier frequency, a numerology to be used may beselected independent of a frequency band.

In addition, in the NR system, a variety of frame structures accordingto the multiple numerologies may be supported.

Hereinafter, an Orthogonal Frequency Division Multiplexing (OFDM)numerology and a frame structure, which may be considered in the NRsystem, will be described.

A plurality of OFDM numerologies supported in the NR system may bedefined as in Table 1.

TABLE 1 μ Δf = 2{circumflex over ( )}μ · 15 [kHz] Cyclic prefix 0 15Normal 1 30 Normal 2 60 Normal, Extended 3 120 Normal 4 240 Normal 5 480Normal

Regarding a frame structure in the NR system, a size of various fieldsin the time domain is expressed as a multiple of a time unit ofTs=1/(Δfmax·Nf). In this case, Δfmax=480·10{circumflex over ( )}3, andNf=4096. DL and UL transmission is configured as a radio frame having asection of Tf=(Δfmax Nf/100)·Ts=100 ms. The radio frame is composed often subframes each having a section of Tsf=(Δfmax Nf/1000)·Ts=1 ms. Inthis case, there may be a set of UL frames and a set of DL frames.

FIG. 2 illustrates a relationship between a UL frame and a DL frame in awireless communication system to which a method proposed by the presentdisclosure may be implemented.

As illustrated in FIG. 2, a UL frame number I from a User Equipment (UE)needs to be transmitted T_TA=N_TA·T_s before the start of acorresponding DL frame in the UE.

Regarding the numerology p, slots are numbered in ascending order ofn{circumflex over ( )}μ_sϵ{0, . . . , N{circumflex over( )}slot,μ_subframe−1} in a subframe, and in ascending order ofn{circumflex over ( )}μ_s,fϵ{0, . . . , N{circumflex over( )}slot,μ_frame−1} in a radio frame. One slot is composed of continuousOFDM symbols of N{circumflex over ( )}μ_symb, and N{circumflex over( )}μ_symb is determined depending on a numerology in use and slotconfiguration. The start of slot n{circumflex over ( )}μ_s in a subframeis temporally aligned with the start of OFDM symbols n{circumflex over( )}μ_s·N{circumflex over ( )}μ_symb in the same subframe.

Not all UEs are able to transmit and receive at the same time, and thismeans that not all OFDM symbols in a DL slot or an UL slot are availableto be used.

Table 2 shows the number of OFDM symbols per slot for a normal CP in thenumerology μ, and Table 3 shows the number of OFDM symbols per slot foran extended CP in the numerology μ.

TABLE 2 Slot configuration 0 1 N{circumflex over ( )} N{circumflex over( )} N{circumflex over ( )} N{circumflex over ( )} N{circumflex over( )} N{circumflex over ( )} μ μ_symb slot, μ_frame μ_symb μ_symb μ_symbslot, μ_subframe 0 14 10 1 7 20 2 1 14 20 2 7 40 4 2 14 40 4 7 80 8 3 1480 8 — — — 4 14 160 16 — — — 5 14 320 32 — — —

TABLE 3 Slot configuration 0 1 N{circumflex over ( )} N{circumflex over( )} N{circumflex over ( )} N{circumflex over ( )} N{circumflex over( )} N{circumflex over ( )} μ μ_symb slot, μ_frame μ_symb μ_symb μ_symbslot, μ_subframe 0 12 10 1 6 20 2 1 12 20 2 6 40 4 2 12 40 4 6 80 8 3 1280 8 — — — 4 12 160 16 — — — 5 12 320 32 — — —

NR Physical Resource

Regarding physical resources in the NR system, an antenna port, aresource grid, a resource element, a resource block, a carrier part,etc. may be considered.

Hereinafter, the above physical resources possible to be considered inthe NR system will be described in more detail.

First, regarding an antenna port, the antenna port is defined such thata channel over which a symbol on one antenna port is transmitted can beinferred from another channel over which a symbol on the same antennaport is transmitted. When large-scale properties of a channel receivedover which a symbol on one antenna port can be inferred from anotherchannel over which a symbol on another antenna port is transmitted, thetwo antenna ports may be in a QC/QCL (quasi co-located or quasico-location) relationship. Herein, the large-scale properties mayinclude at least one of delay spread, Doppler spread, Doppler shift,average gain, and average delay.

FIG. 3 illustrates an example of a resource grid supported in a wirelesscommunication system to which a method proposed by the presentdisclosure may be implemented.

Referring to FIG. 3, a resource grid is composed of N{circumflex over( )}μ_RB·N{circumflex over ( )}RB_SC subcarriers in a frequency domain,each subframe composed of 14·2μ OFDM symbols, but the present disclosureis not limited thereto.

In the NR system, a transmitted signal is described by one or moreresource grids, composed of N{circumflex over ( )}μ_RB·N{circumflex over( )}RB_SC subcarriers, and 2{circumflex over ( )}μ·N{circumflex over( )}(μ)_symb OFDM symbols Herein, N{circumflex over( )}μ_RB<=N{circumflex over ( )}max,μ_RB. The above N{circumflex over( )}max,μ_RB-indicates the maximum transmission bandwidth, and it maychange not just between numerologies, but between UL and DL.

In this case, as illustrated in FIG. 3, one resource grid may beconfigured for the numerology μ and an antenna port p.

Each element of the resource grid for the numerology μ and the antennaport p is indicated as a resource element, and may be uniquelyidentified by an index pair (k, l). Herein, k=0, . . . , N{circumflexover ( )}μ_RB·N{circumflex over ( )}RB_SC−1 is an index in the frequencydomain, and l=0, . . . , 2{circumflex over ( )}μ·N{circumflex over( )}(μ)_symb−1 indicates a location of a symbol in a subframe. Toindicate a resource element in a slot, the index pair (k, l) is used.Herein, l=N{circumflex over ( )}μ_symb−1.

The resource element (k, l) for the numerology μ and the antenna port pcorresponds to a complex value a{circumflex over ( )}(p,u)_k,l. Whenthere is no risk of confusion or when a specific antenna port ornumerology is specified, the indexes p and p may be dropped and therebythe complex value may become a{circumflex over ( )}(p)_k,l or a_k,l.

In addition, a physical resource block is defined as N{circumflex over( )}RB_SC=12 continuous subcarriers in the frequency domain. In thefrequency domain, physical resource blocks may be numbered from 0 toN{circumflex over ( )}μ_RB−1. At this point, a relationship between thephysical resource block number n_PRB and the resource elements (k,l) maybe given as in Equation 1.n_PRB=[k/N{circumflex over ( )}RB_SC]  [Equation 1]

In addition, regarding a carrier part, a UE may be configured to receiveor transmit the carrier part using only a subset of a resource grid. Atthis point, a set of resource blocks which the UE is configured toreceive or transmit are numbered from 0 to N{circumflex over ( )}μ_URB−1in the frequency region.

Self-Contained Subframe Structure

FIG. 4 is a diagram illustrating an example of a self-contained subframestructure in a wireless communication system to which the presentdisclosure may be implemented.

In order to minimize data transmission latency in a TDD system, 5G newRAT considers a self-contained subframe structure as shown in FIG. 4.

In FIG. 4, a diagonal line area (symbol index 0) represents a UL controlarea, and a black area (symbol index 13) represents a UL control area. Anon0shade area may be used for DL data transmission or for UL datatransmission. This structure is characterized in that DL transmissionand UL transmission are performed sequentially in one subframe andtherefore transmission of DL data and reception of UL ACK/NACK may beperformed in the subframe. In conclusion, it is possible to reduce timefor retransmitting data upon occurrence of a data transmission error andthereby minimize a latency of final data transmission.

In this self-contained subframe structure, a time gap is necessary for abase station or a UE to switch from a transmission mode to a receptionmode or to switch from the reception mode to the transmission mode. Tothis end, some OFDM symbols at a point in time of switching from DL toUL in the self-contained subframe structure are configured as a guardperiod (GP).

Analog Beamforming

Since a wavelength is short in a Millimeter Wave (mmW) range, aplurality of antenna elements may be installed in the same size of area.That is, a wavelength in the frequency band 30 GHz is 1 cm, and thus, 64(8×8) antenna elements may be installed in two-dimensional arrangementwith a 0.5 lambda (that is, a wavelength) in 4×4 (4 by 4) cm panel.Therefore, in the mmW range, the coverage may be enhanced or athroughput may be increased by increasing a beamforming (BF) gain with aplurality of antenna elements.

In this case, in order to enable adjusting transmission power and phasefor each antenna element, if a transceiver unit (TXRU) is included,independent beamforming for each frequency resource is possible.However, it is not cost-efficient to install TXRU at each of about 100antenna elements. Thus, a method is considered in which a plurality ofantenna elements is mapped to one TXRU and a direction of beam isadjusted with an analog phase shifter. Such an analog BF method is ableto make only one beam direction over the entire frequency band, andthere is a disadvantage that frequency-selective BF is not allowed.

A hybrid BF may be considered which is an intermediate between digitalBF and analog BF, and which has B number of TXRU less than Q number ofantenna elements. In this case, although varying depending upon a methodof connecting B number of TXRU and Q number of antenna elements, beamdirections capable of being transmitted at the same time is restrictedto be less than B.

Hereinafter, typical examples of a method of connecting TXRU and antennaelements will be described with reference to drawings.

FIG. 5 is an example of a transceiver unit model in a wirelesscommunication system to which the present disclosure may be implemented.

A TXRU virtualization model represents a relationship between outputsignals from TXRUs and output signals from antenna elements. Dependingon a relationship between antenna elements and TXRUs, the TXRUvirtualization model may be classified as a TXRU virtualization modeloption-1: sub-array partition model, as shown in FIG. 5(a), or as a TXRUvirtualization model option-2: full-connection model.

Referring to FIG. 5(a), in the sub-array partition model, the antennaelements are divided into multiple antenna element groups, and each TXRUmay be connected to one of the multiple antenna element groups. In thiscase, the antenna elements are connected to only one TXRU.

Referring to FIG. 5(b), in the full-connection model, signals frommultiple TXRUs are combined and transmitted to a single antenna element(or arrangement of antenna elements). That is, this shows a method inwhich a TXRU is connected to all antenna elements. In this case, theantenna elements are connected to all the TXRUs.

In FIG. 5, q represents a transmitted signal vector of antenna elementshaving M number of co-polarized in one column. W represents a widebandTXRU virtualization weight vector, and W represents a phase vector to bemultiplied by an analog phase shifter. That is, a direction of analogbeamforming is decided by W. x represents a signal vector of M_TXRUnumber of TXRUs.

Herein, mapping of the antenna ports and TXRUs may be performed on thebasis of 1-to-1 or 1-to-many.

TXRU-to-element mapping In FIG. 5 is merely an example, and the presentdisclosure is not limited thereto and may be equivalently applied evento mapping of TXRUs and antenna elements which can be implemented in avariety of hardware forms.

Channel State Information (CSI) Feedback

In most cellular systems including an LTE system, a UE receives a pilotsignal (or a reference signal) for estimating a channel from a basestation, calculate channel state information (CSI), and reports the CSIto the base station.

The base station transmits a data signal based on the CSI informationfed back from the UE.

The CSI information fed back from the UE in the LTE system includeschannel quality information (CQI), a precoding matrix index (PMI), and arank indicator (RI).

CQI feedback is wireless channel quality information which is providedto the base station for a purpose (link adaptation purpose) of providinga guidance as to which modulation & coding scheme (MCS) to be appliedwhen the base station transmits data.

In the case where there is a high wireless quality of communicationbetween the base station and the UE, the UE may feed back a high CQIvalue and the base station may transmit data by applying a relativelyhigh modulation order and a low channel coding rate. In the oppositecase, the UE may feed back a low CQI value and the base station maytransmit data by applying a relatively low modulation order and a highchannel coding rate.

PMI feedback is preferred precoding matrix information which is providedto a base station in order to provide a guidance as to which MIMOprecoding scheme is to be applied when the base station has installedmultiple antennas.

A UE estimates a downlink MIMO channel between the base station and theUE from a pilot signal, and recommends, through PMI feedback, which MIMOprecoding is desired to be applied by the base station.

In the LTE system, only linear MIMO precoding capable of expressing PMIconfiguration in a matrix form is considered.

The base station and the UE share a codebook composed of a plurality ofprecoding matrixes, and each MIMO precoding matrix in the codebook has aunique index.

Accordingly, by feeding back an index corresponding to the mostpreferred MIMO precoding matrix in the codebook as PMI, the UE minimizesan amount of feedback information thereof.

A PMI value is not necessarily composed of one index. For example, inthe case where there are eight transmitter antenna ports in the LTEsystem, a final 8tx MIMO precoding matrix may be derived only when twoindexes (first PMI & second PMI) are combined.

RI feedback is information on the number of preferred transmissionlayers, the information which is provided to the base station in orderto provide a guidance as to the number of the UE's preferredtransmission layers when the base station and the UE have installedmultiple antennas to thereby enable multi-layer transmission throughspatial multiplexing.

The RI and the PMI are very closely correlated to each other. It isbecause the base station is able to know which precoding needs to beapplied to which layer depending on the number of transmission layers.

Regarding configuration of PMI/RM feedback, a PMI codebook may beconfigured with respect to single layer transmission and then PMI may bedefined for each layer and fed back, but this method has a disadvantagethat an amount of PMI/RI feedback information increases remarkably inaccordance with an increase in the number of transmission layers.

Accordingly, in the LTE system, a PMI codebook is defined depending onthe number of transmission layers. That is, for R-layer transmission, Nnumber of Nt×R matrixes are defined (herein, R represents the number oflayers, Nt represents the number of transmitter antenna ports, and Nrepresents the size of the codebook).

Accordingly, in LTE, a size of a PMI codebook is defined irrespective ofthe number of transmission layers. As a result, since PMI/RI is definedin this structure, the number of transmission layers (R) conforms to arank value of the precoding matrix (Nt×R matrix), and, for this reason,the term “rank indicator(RI)” is used.

Unlike PMI/RI in the LTE system, PMI/RI described in the presentdisclosure is not restricted to mean an index value of a precodingmatrix Nt×R and a rank value of the precoding matrix.

PMI described in the present disclosure indicates information on apreferred MINO precoder from among MIMO precoders capable of beingapplied by a transmitter, and a form of the precoder is not limited to alinear precoder which is able to be expressed in a matrix form, unlikein the LTE system. In addition, RI described in the present disclosuremeans wider than RO in LTE and includes feedback information indicatingthe number of preferred transmission layers.

The CSI information may be obtained in all system frequency domains orin some of the frequency domains. In particular, in a broad bandwidthsystem, it may be useful to obtain CSI information on some frequencydomains (e.g., subband) preferred by each UE and then feedback theobtained CSI information.

In the LTE system, CSI feedback is performed via an UL channel, and, ingeneral, periodic CSI feedback is performed via a physical uplinkcontrol channel (PUCCH) and aperiodic CSI feedback is performed viaphysical uplink shared channel (PUSCH) which is a UL data channel.

The aperiodic CSI feedback means temporarily transmitting a feedbackonly when a base station needs CSI feedback information, and the basestation triggers the CSI feedback via a DL control channel such as aPDCCH/ePDCCH.

In the LTE system, which information a UE needs to feedback in responseto triggering of CSI feedback is defined as a PUSCH CSI reporting mode,as shown in FIG. 8, and a PUSCH CSI reporting mode in which the UE needsto operate is informed for the UE in advance via a higher layer message.

Channel State Information (CSI)-Related Procedure

In the new radio (NR) system, a channel state information-referencesignal (CSI-RS) is used for time/frequency tracking, CSI computation,layer 1(L1)-reference signal received power (RSRP) computation, ormobility

Throughout the present disclosure, “A and/or B” may be interpreted asthe same as “including at least one of A or B”.

The CSI computation is related to CSI acquisition, and L1-RSRPcomputation is related to beam management (BM).

The CSI indicates all types of information indicative of a quality of aradio channel (or link) formed between a UE and an antenna port.

Hereinafter, operation of a UE with respect to the CSI-related procedurewill be described.

FIG. 6 is a flowchart illustrating an example of a CSI-relatedprocedure.

To perform one of the above purposes of a CSI-RS, a terminal (e.g., aUE) receives CSI related configuration information from a base station(e.g., a general node B (gNB)) through a radio resource control (RRC)signaling (S610).

The CSI-related configuration information may include at least one ofCSI interference management (IM) resource-related information, CSImeasurement configuration-related information, CSI resourceconfiguration-related information, CSI-RS resource-related information,or CSI report configuration-related information.

The CSIIM resource-related information may include CSI-IM resourceinformation, CSI-IM resource set information, etc.

The CSI-IM resource set is identified by a CSI-IM resource set ID(identifier), and one resource set includes at least one CSI-IMresource.

Each CSI-IM resource is identified by a CSI-IM resource ID.

The CSI resource configuration-related information defines a groupincluding at least one of a non-zero power (NZP) CSI-RS resource set, aCSI-IM resource set, or a CSI-SSB resource set.

That is, the CSI resource configuration-related information includes aCSI-RS resource set list, and the CSI-RS resource set list may includeat least one of a NZP CSI-RS resource set list, a CSI-IM resource setlist, or a CSI-SSB resource set list.

The CSI resource configuration-related information may be expressed asCSI-REsourceConfig IE.

The CSI-RS resource set is identified by a CSI-RS resource set ID, andone resource set includes at least one CSI-RS resource.

Each CSI-RS resource is identified by a CSI-RS resource ID.

As shown in Table 4, parameters (e.g.: the BM-related parameterrepetition, and the tracking-related parameter trs-Info indicative of(or indicating) a purpose of a CSI-RS may be set for each NZP CSI-RSresource set.

Table 4 shows an example of NZP CSI-RS resource set IE.

TABLE 4 -- ASN1START -- TAG-NZP-CSI-RS-RESOURCESET-STARTNZP-CSI-RS-ResourceSet ::= SEQUENCE { nzp-CSI-ResourceSetIdNZP-CSI-RS-ResourceSetId, nzp-CSI-RS-Resources SEQUENCE (SIZE(1..maxNrofNZP-CSI-RS-ResourcesPerSet)) OF repetitionNZP-CSI-RS-ResourceId, ENUMERATED {on, off} OPTIONAL,aperiodicTriggeringOffset INTEGER(0..4) OPTIONAL, -- Need S trs-InfoENUMERATED {true} OPTIONAL, -- Need R ... } --TAG-NZP-CSI-RS-RESOURCESET-STOP -- ASN1STOP

In Table 4, the parameter repetition is a parameter indicative ofwhether to repeatedly transmit the same beam, and indicates whetherrepetition is set to “ON” or “OFF” for each NZP CSI-RS resource set.

The term “transmission (Tx) beam” used in the present disclosure may beinterpreted as the same as a spatial domain transmission filter, and theterm “reception (Rx) beam” used in the present disclosure may beinterpreted as the same as a spatial domain reception filter.

For example, when the parameter repetition in Table 4 is set to “OFF”, aUE does not assume that a NZP CSI-RS resource(s) in a resource set istransmitted to the same DL spatial domain transmission filter and thesame Nrofports in all symbols.

In addition, the parameter repetition corresponding to a higher layerparameter corresponds to “CSI-RS-ResourceRep” of L1 parameter.

The CSI report configuration related information includes the parameterreportConfigType indicative of a time domain behavior and the parameterreportQuantity indicative of a CSI-related quantity to be reported.

The time domain behavior may be periodic, aperiodic, or semi-persistent.

In addition, the CSI report configuration-related information may berepresented as CSI-ReportConfig IE, and Table 5 shows an example of theCSI-ReportConfig IE.

TABLE 5 -- ASN1START -- TAG-CSI-RESOURCECONFIG-START CSI-ReportConfig::= SEQUENCE { reportConfigId CSI-ReportConfigId, carrier ServCellIndexOPTIONAL, -- Need S resourcesForChannelMeasurement CSI-ResourceConfigId,csi-IM-ResourcesForInterference CSI-ResourceConfigId OPTIONAL, -- Need Rnzp-CSI-RS-ResourcesForInterference CSI-ResourceConfigId OPTIONAL, --Need R reportConfigType CHOICE { periodic SEQUENCE { reportSlotConfigCSI-ReportPeriodicityAndOffset, pucch-CSI-ResourceList SEQUENCE (SIZE(1..maxNrofBWPs)) OF PUCCH-CSI-Resource }, semiPersistentOnPUCCHSEQUENCE { reportSlotConfig CSI-ReportPeriodicityAndOffset,pucch-CSI-ResourceList SEQUENCE (SIZE (1..maxNrofBWPs)) OFPUCCH-CSI-Resource }, semiPersistentOnPUSCH SEQUENCE { reportSlotConfigENUMERATED (sl5, sl10, sl20, sl40, sl80, sl160, sl320),reportSlotOffsetList SEQUENCE (SIZE (1.. maxNrofUL-Allocations)) OFINTEGER(0..32), p0alpha P0-PUSCH-AlphaSetId }, aperiodic SEQUENCE {reportSlotOffsetList SEQUENCE (SIZE (1..maxNrofUL-Allocations)) OFINTEGER(0..32) } }, reportQuantity CHOICE { none NULL, cri-RI-PMI-CQINULL, cri-RI-i1 NULL, cri-RI-i1-CQI SEQUENCE { pdsch-BundleSizeForCSIENUMERATED {n2, n4) OPTIONAL }, cri-RI-CQI NULL, cri-RSRP NULL,ssb-Index-RSRP NULL, cri-RI-LI-PMI-CQI NULL },

In addition, the UE measures CSI based on configuration informationrelated to the CSI (S620).

Measuring the CSI may include (1) receiving a CSI-RS by the UE (S621)and (2) computing CSI based on the received CSI-RS (S622).

A sequence for the CSI-RS is generated by Equation 2, and aninitialization value of a pseudo-random sequence C(i) is defined byEquation 3.

$\begin{matrix}{{r(m)} = {{\frac{1}{\sqrt{2}}\left( {1 - {2 \cdot {c\left( {2\; m} \right)}}} \right)} + {j\frac{1}{\sqrt{2}}\left( {1 - {2 \cdot {c\left( {{2\; m} + 1} \right)}}} \right)}}} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack \\{c_{init} = {\left( {{2^{10}\left( {{N_{symb}^{slot}n_{s,f}^{\mu}} + l + 1} \right)\left( {{2\; n_{ID}} + 1} \right)} + n_{ID}} \right){mod}\; 2^{31}}} & \left\lbrack {{Equation}\mspace{14mu} 3} \right\rbrack\end{matrix}$

In Equations 2 and 3, n_(s,f) ^(μ) is a slot number within a radioframe, and a pseudo-random sequence generator is initialized with Cintat the start of each OFDM symbol where n_(s,f) ^(μ) is the slot numberwithin a radio frame.

In addition, l indicates an OFDM symbol number in a slot, and indicateshigher-layer parameter scramblingID.

In addition, regarding the CSI-RS, resource element (RE) mapping ofCSI-RS resources of the CSI-RS is performed in time and frequencydomains by higher layer parameter CSI-RS-ResourceMapping.

Table 6 shows an example of CSI-RS-ResourceMapping IE.

TABLE 6 -- ASN1START -- TAG-CSI-RS-RESOURCEMAPPING-STARTCSI-RS-ResourceMapping ::= SEQUENCE { frequencyDomainAllocation CHOICE {row1 BIT STRING (SIZE (4)), row2 BIT STRING (SIZE (12)), row4 BIT STRING(SIZE (3)), other BIT STRING (SIZE (6)) }, nrofPorts ENUMERATED{p1,p2,p4,p8,p12,p16,p24,p32}, firstOFDMSymbolInTimeDomain INTEGER(0..13), firstOFDMSymbolInTimeDomain2 INTEGER (2..12) OPTIONAL, -- NeedR cdm-Type ENUMERATED {noCDM, fd-CDM2, cdm4-FD2-TD2, cdm8-FD2- TD4},density CHOICE { dot5 ENUMERATED (evenPRBs, oddPRBs}, one NULL, threeNULL, spare NULL }, freqBand CSI-FrequencyOccupation, ... }

In Table 6, a density (D) indicates a density of CSI-RS resourcesmeasured in a RE/port/physical resource block (PRB), and nrofPortsindicates the number of antenna ports.

In addition, the UE reports the measured CSI to the base station (S630).

Herein, when a quantity of CSI-ReportConfig in Table 6 is set to“none(or No report)”, the UE may skip the reporting.

However, even when the quantity is set to “none(or No report)”, the UEmay report the measured CSI to the base station.

The case where the quantity is set to “none” is t when an aperiodic TRSis triggered or when repetition is set.

Herein, it may be defined such that reporting by the UE is omitted onlywhen repetition is set to “ON”.

To put it briefly, when repetition is set to “ON” and “OFF”, a CSIreport may indicate any one of “No report”, “SSB Resource Indicator(SSBRI) and L1-RSRP”, and “CSI-RS Resource Indicator (CRI) and L1-RSRP”.

Alternatively, it may be defined to transmit a CSI report indicative of“SSBRI and L1-RSRP” or “CRI and L1-RSRP” when repetition is set to“OFF”, it may be defined such that, and to transmit a CSI reportindicative of “No report”, “SSBRI and L1-RSRP”, or “CRI and L1-RSRP”when repetition is “ON”.

Beam Management (BM) Procedure

Beam management (BM) defined in New Radio (NR) will be described.

BM procedures are layer 1(L1)/layer 2(L2) procedures for acquiring andmaintaining a set of beams from a base station (e.g. a gNB, TRP, etc.)and/or a terminal (e.g., a UE) to be used for DL and ULtransmission/reception, and the BM procedures may include the followingprocedures and terms.

-   -   Beam measurement: An operation of measuring properties of a        received beam forming signal by a base station or a UE    -   Beam determination: An operation of selecting its own        transmission (Tx) beam/reception (Rx) beam by a base station or        a UE    -   Beam sweeping: An operation of covering a spatial domain using a        Tx/Rx beam for a predetermined time interval in a predetermined        method    -   Beam report: An operation of reporting information of a        beam-formed signal by a UE based on beam measurement

FIG. 7 is a conceptual diagram illustrating an example of a beam-relatedmeasurement model.

For beam measurement, an SS block (or an SS/PBCH block (SSB)) or aCRI-RS) is used in DL, and an sounding reference signal (SRS) is used inUL.

In RRC-CONNECTED, a UE may measure a plurality of beams (at least onebeam) in a cell, and the UE may average the measurements (RSRP, RSRQ,SINR, etc.) to derive a cell quality.

In doing so, the UE may be configured to consider a sub-set of adetected beam(s).

Beam measurement-related filtering is performed at two different levels(at the physical layer which induces a beam quality and at the RRC levelwhich induces a cell quality from multiple beams).

The cell quality may be induced from the beam measurements in the samemanner with respect to both of a cell quality of a serving cell (s) anda cell quality of a non-serving cell(s).

If the UE is configured by the gNB to report a measurement of a specificbeam(s), a measurement report includes measurements of X number of bestbeams. The beam measurement may be reported as L1-RSRP.

In FIG. 7, K number of beams (gNB beam 1, gNB beam 2, . . . , gNB beamk) 710 are configured by the gNB for L3 mobility, and correspond to ameasurement of an SS (synchronized signal) block (SSB) or a CSI-RSresource detected by the UE in L1.

In FIG. 7, Layer 1 filtering 720 means inner Layer 1 filtering of inputsmeasured at point A.

In addition, in Beam Consolidation/Selection 730, a beam-specificmeasurement is consolidated (or integrated) to induce a cell quality.

Layer 3 filtering 740 for a cell quality means filtering performed onmeasurements provided at point B.

The UE evaluates a reporting criterion whenever a new measurement isreported at least at points C and C1.

D corresponds to measurement report information (message) transmitted ona wireless interface.

In L3 beam filtering 750, filtering is performed on a measurement (abeam-specific measurement) provided at point A1.

In beam selection 760 for beam reporting, X number of measurementsprovided at point E is selected.

F indicates beam measurement information included in a measurementreport (transmitted) on a wireless interface.

In addition, the BM procedures may be classified into (1) a DL BMprocedure using a synchronization signal (SS)/physical broadcast channel(PBCH) Block or a CSI-RS, and (2) a UL BM procedure using an SRS.

In addition, each BM procedure may include Tx beam weeping fordetermining a Tx beam, and Rx beam sweeping for determining an Rx beam.

DL BM Procedure

First, the DL BM procedure will be described.

The DL BM procedure may include (1) transmitting a beamformed DL RS(reference signals) (e.g., a CSI RS or a SS Block (SSB)) of a basestation, and (2) beam reporting by a UE.

Herein, the beam reporting may include a preferred DL RS ID(identifier)(s) and L1-RSRP corresponding thereto.

The DL RS ID may be a SSB Resource Indicator (SSBRI) or a CSI-RSResource Indicator (CRI).

FIG. 8 is a diagram illustrating a Tx beam regarding the DL BMprocedure.

As illustrated I FIG. 8, an SSB beam and a CSI-RS beam may be used forbeam measurement.

Herein, a measurement metric is L1-RSRP for each resource/block.

An SSB may be used for coarse beam measurement, and a CSI-RS may be usedfor fine beam measurement.

In addition, the SSB may be used for both Tx beam sweeping and Rx beamsweeping.

The Rx beam sweeping using the SSB may be performed in a manner in whicha UE changes an Rx beam for the same SSBRI across a plurality of SSBburst.

Herein, a single SS burst includes one or more SSBs, and a single SSburst set includes one or more SSB bursts.

DL BM Procedure Using SSB

FIG. 9 is a flowchart illustrating an example of the DL BM procedureusing SSB.

Configuration of a beam report using an SSB is performed upon CSI/beamconfiguration in an RRC connected state (or RRC connected mode).

Like CSI-ResourceConfig IE in Table 7, BM configuration using an SSB isnot defined additionally, and the SSB is set as a CSI-RS resource.

Table. 7 shows an example of CSI-ResourceConfig IE.

TABLE 7 -- ASN1START -- TAG-CSI-RESOURCECONFIG-START CSI-ResourceConfig::= SEQUENCE { csi-ResourceConfigId CSI-ResourceConfigId,csi-RS-ResourceSetList CHOICE { nzp-CSI-RS-SSB SEQUENCE {nzp-CSI-RS-ResourceSetList SEQUENCE (SIZE (1..maxNrofNZP-CSI-RS-ResourceSetsPerConfig)) OF NZP-CSI-RS-ResourceSetId OPTIONAL,csi-SSB-ResourceSetList SEQUENCE (SIZE (1..maxNrofCSI-SSB-ResourceSetsPerConfig)) OF CSI-SSB-ResourceSetId OPTIONAL },csi-IM-ResourceSetList SEQUENCE (SIZE (1..maxNrofCSI-IM-ResourceSetsPerConfig)) OF CSI-IM-ResourceSetId }, bwp-Id BWP-Id,resourceType ENUMERATED { aperiodic, semiPersistent, periodic }, ... }-- TAG-CSI-RESOURCECONFIGTOADDMOD-STOP -- ASN1STOP

In Table 7, the parameter csi-SSB-ResourceSetList indicates a list ofSSB resources used for beam management and reports in a single resourceset.

The UE receives, from the base station, CSI-ResourceConfig IE includingCSI-SSB-ResourceSetList which includes SSB resources used for BM (S910).

Herein, the SSB resource set may be configured as {SSBx1, SSBx2, SSBx3,SSBx4, . . . }.

An SSB index may be defined from 0 to 63.

The UE receives the SSB resources from the base station based on theCSI-SSB-ResourceSetList (S920).

In addition, when CSI-RS reportConfig for SSBRI and L1-RSRP reporting isconfigured, the UE (beam) reports the best SSBRI and L1-RSRPcorresponding thereto to the base station (S930).

That is, when reportQuantity in the CSI-RS reportConfig IE is configuredas ssb-Index-RSRP, the UE reports the best SSBRI and L1-RSRPcorresponding thereto to the base station.

In addition, when a CSI-RS resource is configured in an OFDM symbol(s)identical to an SSB (SS/PBCH Block) and QCL-TypeD is applicable, the UEmay assume that the CSI-RS and the SSB are quasi co-located with eachother in terms of “QCL-TypeD”.

Herein, the QCL Type D may mean that antenna ports are QCL with eachother in terms of the spatial Rx parameter. When the UE receives aplurality of DL antenna ports which are in a QCL Type D relationshipwith each other, it is possible to apply the same Rx beam.

In addition, the UE does not expect that a CSI-RS is configured in an REoverlapping with a RE of the SSB.

DL BM Procedure Using CSI-RS

When a UE receives configuration of NZP-CSI-RS-ResourceSet in which(higher layer parameter) repetition is set to “ON”, the UE may assumethat at least one CSI-RS resource in NZP-CSI-RS-ResourceSet istransmitted to the same downlink spatial domain transmission filter.

That is, at least one CSI-RS resource in the NZP-CSI-RS-ResourceSet istransmitted via the same Tx beam.

Herein, at least one CSI-RS resource in the NZP-CSI-RS-ResourceSet maybe transmitted via a different OFDM symbol or may be transmitted in adifferent frequency domain (that is, via FDM).

The case where the at least one CSI-RS resource is subject to FDM iswhen the UE is a multi-panel UE.

In addition, the case where repetition is set to “ON” relates to an Rxbeam sweeping procedure of the UE.

The UE does not expect to receive different periodicities atperiodicityAndOffset from all CSI-RS resources in theNZP-CSI-RS-Resourceset.

In addition, when the repetition is set to “OFF”, the UE does not assumethat at least one CSI-RS resource in the NZP-CSI-RS-Resourceset istransmitted to the same downlink spatial domain transmission filter.

That is, at least one CSI-RS resource in the NZP-CSI-RS-Resourceset istransmitted via a different TX beam.

The case where the repetition is set to “OFF” relates to a Tx beamsweeping procedure of a base station.

In addition, the parameter repetition may be set only for CSI-RSresource sets that are associated with CSI-ReportConfig having a reportof L1 RSRP or “No Report or None”.

If the UE receives CSI-ReportConfig in which reportQuantity is set to“cri-RSRP” or “none” and, CSI-ResourceConfig for channel measurement(higher layer parameter “resourcesForChannelMeasurement”) does notinclude higher layer parameter “trs-Info′ but includesNZP-CSI-RS-ResourceSet” which is set to higher layer parameter“repetition” (repetition=ON), the UE may be composed of a port of thesame number (1-port or 2-port), which includes higher layer parameter“nrofPorts” for all CSI-RS resources in the NZP-CSI-RS-ResourceSet.

More specifically, regarding the purpose of a CSI-RS, if the parameterrepetition is set in a specific CSI-RS resource set and TRS_info is notset, the CSI-RS is used for beam management.

In addition, if the parameter repetition is not set and TRS info is set,the CSI-RS is used for a tracking reference signal (TRS).

In addition, if neither the parameter repetition nor TRS_info isconfigured, the CSI-RS is used for CSI acquisition.

FIG. 10 is a diagram illustrating an example of a DL BM procedure usinga CSI-RS.

FIG. 10a shows an Rx beam determination (or refinement) procedure of aUE, and FIG. 10b shows a Tx beam determination procedure of a basestation.

In addition, FIG. 10a shows the case where the parameter repetition isset to “ON”, and FIG. 10b shows the case where the parameter“repetition” is set as “OFF”.

With reference to FIGS. 10A and 11, the Rx beam determination procedureof the UE will be described.

FIG. 11 is a flowchart illustrating an example of the Rx beamdetermination procedure of the UE.

The UE receives, from the base station, NZP CSI-RS resource set IEincluding higher layer parameter repetition through RRC signaling(S1110).

The parameter repetition is set to “ON”.

The UE repeatedly receives a resource(s) in a CSI-RS resource set, inwhich repetition is set to “ON”, from a different OFDM symbol throughthe same Tx beam (or a DL spatial domain transmission filter) (S1120).

In doing so, the UE determines its own Rx beam (S1130).

The UE may omit a CSI report or may transmit a CSI report includingCRI/L1-RSRP to the base station (S1140).

In this case, reportQuantity of CSI report Config may be configured as“No report (or None)” or “CRI and L1-RSRP”.

That is, when the repetition is set to “ON”, the UE may omit a CSIreport or may report ID information (CRI) of a beam pair-relatedpreferred beam and a quality value thereof (L1-RSRP).

With reference to FIGS. 10b and 12, the Tx beam determination procedureof the base station will be described.

FIG. 12 is a flowchart illustrating an example of the Tx beamdetermination procedure of the base station.

A UE receives, from the base station, NZP CSI-RS resource set IEincluding higher layer parameter repetition through RRC signaling(S1210).

The parameter repetition is set to “OFF” and relates to a Tx beamsweeping procedure of the base station.

In addition, the UE receives resources in a CSI-RS resource set, inwhich repetition is set to “OFF”, via a different Tx beam (a DL spatialdomain transmission filter) (S1220).

In addition, the UE selects (or determines) the best beam (S1230), andreports ID and quality information (e.g., L1-RSRP) of the selected beamto the base station (S1240).

In this case, reportQuantity of CSI report Config may be configured as“CRI+L1-RSRP”.

That is, when the CSI-RS is transmitted for BM, the UE reports CSI andL1-RSRP corresponding thereto to the base station.

FIG. 13 is a diagram illustrating an example of resource allocation intime and frequency domains, which is related to operation of FIG. 10.

That is, when repetition is set to “ON” for a CSI-RS resource set, aplurality of CSI-RS resources is repeatedly used via the same Tx beam,and, when repetition is set to “OFF” for the CSI-RS resource set,different CSI-RS resources are transmitted via different Tx beams.

DL BM-Related Beam Indication

A UE may receive RRC configuration of a list of a maximum M number ofcandidate Transmission Configuration Indication (TCI) states at leastfor the purpose of Quasi Co-location (CQL) indication. Herein, M may be64.

Each TCI state may be configured as one RS set.

ID of each DL RS for a spatial QCL at least in an RS set (QCL Type D)may refer to at least one of DL RS types such as an SSB, a P-CSI RS, aSP-CSI RS, or a A-CSI RS.

Initialization/update of ID of DL RS(s) in an RS set used at least for aspatial QCL purpose may be performed at least via explicit signaling.

Table 8 shows an example of TCI-State IE.

The TCI-State IE is associated with a quasi co-location (QCL) typecorresponding to one or two DL reference signals (RSs).

TABLE 8 -- ASN1START -- TAG-TCI-STATE-START TCI-State ::= SEQUENCE {tci-StateId TCI-StateId, qcl-Type1 QCL-Info, qcl-Type2 QCL- InfoOPTIONAL, -- Need R ... } QCL-Info ::= SEQUENCE { cell ServCellIndexOPTIONAL, -- Need R bwp-Id BWP- Id OPTIONAL, -- Cond CSI-RS- IndicatedreferenceSignal CHOICE { csi-rs NZP-CSI-RS-ResourceId, ssb SSB-Index },qcl-Type ENUMERATED {typeA, typeB, typeC, typeD}, ... } --TAG-TCI-STATE-STOP -- ASN1STOP

In Table 8, the parameter “bwp-id” indicates a BL BWP where a RS islocated, and the parameter “cell” indicates a carrier where an RS islocated, and the parameter “referencesignal” indicates a referenceantenna port(s) which is a quasi colocation source for a correspondingtarget antenna port(s). The target antenna port(s) may be an example ofa CSI-RS, a PDCCH DMRS, or a PDSCH DMRS. For example, in order toindicate QCL reference information for a NZP CSI-RS, TCI state ID may beindicated in each CORESET configuration. In another example, in order toindicate QCL reference information for a PDSCH DMRS antenna port(s), DCIstate ID may be indicated via DCI.

QCL (Quasi-Co Location)

An antenna port is defined such that a channel over which a symbol onone antenna port is carried can be inferred from another channel overwhich a symbol on another antenna port is carried. When properties ofthe channel over which a symbol on one antenna port is carried can beinferred from a channel over which a symbol on another antenna port iscarried, the two antenna ports may be in a quasi co-located or quasico-location (QC/QCL) relationship.

Herein, the channel properties may include at least one of delay spread,Doppler spread, Doppler shift, average gain, and average delay. Herein,the spatial Rx parameter indicates a spatial (reception) channelproperty parameter such as an angle of arrival.

In order to decode a PDSCH according to a PDCCH which is detected andhas DCI intended for a corresponding UE and a given serving cell, a listof M number of TCI-state configurations in higher layer parameterPDSCH-Config may be set. The number M depends on UE capability.

Each TCI-State includes a parameter for setting a quasi co-locationrelationship between one or two DL reference signals and a DMRS port ofthe PDSCH.

The quasi co-location relationship may be configured as higher layerparameter qcl-Type 1 for the first DL RS and qcl-Type 2 (when set) forthe second DL RS.

If there are the two DL RSs, a QCL type is not the same, regardless ofwhether the two DL RSs have the same reference or different references.

A quasi co-location type corresponding to each DL RS is given by higherlayer parameter “qcl-Type” in QCL-Info, and may take one of thefollowing forms.

-   -   ‘QCL-TypeA’: {Doppler shift, Doppler spread, average delay,        delay spread}    -   ‘QCL-TypeB’: {Doppler shift, Doppler spread}    -   ‘QCL-TypeC’: {Doppler shift, average delay}    -   ‘QCL-TypeD’: {Spatial Rx parameter}

For example, in the case where a target antenna port is a specific NZPCSI-RS, corresponding NZP CSI-RS antenna ports may beindicated/configured to be QCL with a specific TRS in terms of QCL-TypeA or with a specific SSB in terms of QCL-Type D. The UEindicated/configured as above may receive a corresponding NZP CSI-RSusing a measured Doppler and a delay value, and may apply a Rx beam,which is used in receiving the QCL-TypeD SSB, to receive thecorresponding NZP CSI-RS.

The UE receives an activation command used to map eight TCI states tocodepoints of a DCI field “Transmission Configuration Indication”.

UL BM Procedure

In UL BM, beam reciprocity (or beam correspondence) between a Tx beamand an Rx beam may or may not be achieved depending on how a UE isimplemented.

If reciprocity between Tx beam and Rx beam is established both in a basestation and in a UE, it is possible to discover a UL beam pair using aDL beam pair.

However, if the reciprocity between Tx beam and Rx beam is notestablished in any one of the base station or the UE, a UL beam pairdetermination procedure is required separately from a DL beam pairdetermination procedure.

In addition, even in the case where both the base station and the UEmaintains beam correspondence, the base station is able to use the UL BMprocedure to determine a DL Tx beam even without the UE's request for areport of a preferred beam.

UL BM may be performed by transmitting a beamformed UL SRS, and“SRS-SetUse” is configured as “BeamManagement”.

Similarly, the UL BM procedure may be classified into Tx beam sweepingby the UE and Rx beam sweeping by the base station.

The UE may receive (through higher layer signaling, RRC signaling, etc.)configuration of one or more SRS resource sets which are configured by(higher layer parameter) “SRS-ResourceSet”.

Regarding each SRS resource set, the UE may receive configuration of K≥1SRS resources (higher later parameter SRS-resource).

Herein, K is a natural number, and the maximum value of K is indicatedby SRS_capability.

Whether to apply UL BM of the SRS resource set is configured by (higherlayer parameter) SRS-SetUse.

If the parameter SRS-SetUse is configured as ‘BeamManagement(BM)’, onlyone SRS resource may be transmitted to each of multiple SRS resourcesets at a given time instant.

FIG. 14 is a diagram illustrating an example of the UL BM procedureusing an SRS.

Specifically, FIG. 14a shows an RX beam determination procedure by abase station, and FIG. 14b shows a Tx beam determination procedure by aUE.

FIG. 15 is a flowchart illustrating a UL BM procedure using an SRS.

First, a UE receives, from a base station, an RRC signaling (e.g.,SRS-Config IE) including (higher layer parameter) usage parameter whichis configured as “beam management” (S1510).

Table 9 shows an example of SRS-Config information element (IE), and theSRS-Config IE is used for SRS transmission configuration.

The SRS-Config IE includes a SRS-Resource list and a SRS-ResourceSetlist.

Each SRS resource set indicates a set of SRS-resources.

A network triggers transmission of the SRS resource set usingaperiodicSRS-ResourceTrigger (L1 DCI) which has been configured.

TABLE 9 -- ASN1START -- TAG-MAC-CELL-GROUP-CONFIG-START SRS-Config ::=SEQUENCE { srs-ResourceSetToReleaseList SEQUENCE(SIZE(1..maxNrofSRS-ResourceSets)) OF SRS-ResourceSetId OPTIONAL, --Need N srs-ResourceSetToAddModList SEQUENCE(SIZE(1..maxNrofSRS-ResourceSets)) OF SRS- ResourceSet OPTIONAL, -- NeedN srs-ResourceToReleaseList SEQUENCE (SIZE(1..maxNrofSRS-Resources)) OFSRS- ResourceId OPTIONAL, -- Need N srs-ResourceToAddModList SEQUENCE(SIZE(1..maxNrofSRS-Resources)) OF SRS- Resource OPTIONAL, -- Need Ntpc-Accumulation ENUMERATED {disabled} OPTIONAL, -- Need S ... }SRS-ResourceSet ::= SEQUENCE { srs-ResourceSetId SRS-ResourceSetId,srs-ResourceIdList SEQUENCE (SIZE(1..maxNrofSRS-ResourcesPerSet)) OFSRS-ResourceId OPTIONAL, -- Cond Setup resourceType CHOICE { aperiodicSEQUENCE { aperiodicSRS-ResourceTrigger INTEGER(1..maxNrofSRS-TriggerStates-1), csi-RS NZP-CSI-RS- ResourceId OPTIONAL,-- Cond NonCodebook slotoffset INTEGER (1..32) OPTIONAL, -- Need S ...}, semi-persistent SEQUENCE { associatedCSI-RS NZP-CSI-RS- ResourceIdOPTIONAL, -- Cond NonCodebook ... }, periodic SEQUENCE {associatedCSI-RS NZP-CSI-RS- ResourceId OPTIONAL, -- Cond NonCodebook... } }, usage ENUMERATED {beamManagement, codebook, nonCodebook,antennaSwitching}, alpha Alpha OPTIONAL, -- Need S p0 INTEGER (−202..24) OPTIONAL, -- Cond Setup pathlossReferenceRS CHOICE { ssb-IndexSSB-Index, csi-RS-Index NZP-CSI-RS-ResourceId SRS-SpatialRelationInfo::= SEQUENCE { servingCellId ServCellIndex OPTIONAL, -- Need SreferenceSignal CHOICE { ssb-Index SSB-Index, csi-RS-IndexNZP-CSI-RS-ResourceId, srs SEQUENCE { resourceId SRS-ResourceId,uplinkBWP BWP-Id } } } SRS-ResourceId ::= INTEGER(0..maxNrofSRS-Resources-1)

In Table 9, usage indicates a higher layer parameter indicative ofwhether the SRS resource set is used for beam management or forcodebook-based or non-codebook-based transmission.

The usage parameter corresponds to L1 parameter “SRS-SetUse”.

“spatialRelationInfo” is a parameter indicative of configuration of arelation between a reference RS and a target SRS.

Herein, the reference RS may be an SSB, a CSI-RS, or an SRScorresponding to L1 parameter “SRS-SpatialRelationInfo”.

The usage is configured for each SRS resource set.

In addition, the UE determines a Tx beam for an SRS resource to betransmitted, based on SRS-SpatialRelation Info included in theSRS-Config IE (S1520).

Herein, SRS-SpatialRelation Info is configured for each SRS resource andindicates whether to apply the same beam as a beam used in an SBS, aCSI-RS, or an SRS for each SRS resource.

In addition, SRS-SpatialRelationInfo may or may not be configured foreach SRS resource.

If SRS-SpatialRelationInfo is configured for an SRS resource, theSRS-SpatialRelationInfo is transmitted via the same beam as a beam usedin an SSB, a CSI-RS, or an SRS.

However, if SRS-SpatialRelationInfo is not configured in an SRSresource, the UE may determine an arbitrary Tx beam and transmit an SRSvia the determined Tx beam (S1530).

More specifically, a P-SRS of which ‘SRS-ResourceConfigType’ isconfigured as ‘periodic’ will be described.

(1) When SRS-SpatialRelationInfo is configured as ‘SSB/PBCH’, the UEtransmits a corresponding SRS resource by applying a spatial domaintransmission filter identical to (or generated by) a spatial domain Rxfilter used to receive an SSB.PBCH, or

(2) When SRS-SpatialRelationInfo us configured as“CSI-RS”, the UEtransmits a corresponding SRS resource having the same spatial domaintransmission filter used to receive a periodic CSI-RS or an SP CSI-RS,or

(3) When SRS-SpatialRelationInfo is configured as “SRS”, the UEtransmits a corresponding SRS resource by applying the same spatialdomain transmission filter used to transmit a periodic SRS.

Even when ‘SRS-ResourceConfigType’ is configured as “SP-SRS” or“AP-SRS”, the above may be applied in the same manner.

Additionally, the UE may or may not receive a feedback on an SRS fromthe base station in the following three cases (S1540).

First, when Spatial_Relation_Info is configured for all SRS resources inan SRS resource set, the UE transmits an SRS via a beam indicated by thebase station.

For example, Spatial_Relation_Info indicates the same SSB, CRI or SRI,the UE repeatedly transmits an SRS via the same beam.

This case corresponds to FIG. 14a which is about a purpose of selectingan Rx beam by the base station.

Second, Spatial_Relation_Info may not be configured for all SRSresources in an SRS resource set.

In this case, the UE may perform transmission by freely changing an SRSbeam.

That is, this case corresponds to FIG. 14b which is about a purpose ofselecting a Tx beam by the UE.

Lastly, Spatial_Relation_Info may be configured only for some SRSresources in an SRS resource set.

In this case, the UE may transmit an SRS via an indicated beam to theSRS resources for which Spatial_Relation_Info is configured, and the UEmay transmit an SRS to other SRS resources, in whichSpatial_Relation_Info is not configured, via an arbitrary Tx beam.

CSI Measurement and Reporting Procedure

The NR system supports more flexible and dynamic CSI measurement andreporting.

The CSI measurement may include receiving a CSI-RS, and acquiring CSI bycomputing the received CSI-RS.

As time domain behaviors of CSI measurement and reporting,aperiodic/semi-persistent/periodic channel measurement (CM) andinterference measurement (IM) are supported.

To configure CSI-IM, four port NZP CSI-RS RE patterns are used.

CSI-IM-based IMR of NR has a design similar to CSI-IM of LTE and isconfigured independent of ZP CSI-RS resources for PDSCH rate matching.

In addition, each port in the NZP CSI-RS-based IMR emulates aninterference layer having (a desirable channel and) a pre-coded NZPCSI-RS.

This is about intra-cell interference measurement of a multi-user case,and it primarily targets MU interference.

At each port of the configured NZP CSI-RS-based IMR, the base stationtransmits the pre-coded NZP CSI-RS to the UE.

The UE assumes a channel/interference layer for each port in a resourceset, and measures interference.

If there is no PMI or RI feedback for a channel, a plurality ofresources are configured in a set and the base station or networkindicates, through DCI, a subset of NZP CSI-RS resources forchannel/interference measurement.

Resource setting and resource setting configuration will be described inmore detail.

Resource Setting

Each CSI resource setting “CSI-ResourceConfig” includes configuration ofS CSI resource set (which is given by higher layer parameter“csi-RS-ResourceSetList”).

Herein, a CSI resource setting corresponds to CSI-RS-resourcesetlist.

Herein, S represents the number of configured CSI-RS resource sets.

Herein, configuration of S CSI resource set includes each CSI resourceset including CSI-RS resources (composed of NZP CSI-RS or CSI-IM), and aSS/PBCH block (SSB) resource used for L1-RSRP computation.

Each CSI resource setting is positioned at a DL bandwidth part (BWP)identified by higher layer parameter bwp-id.

In addition, all CSI resource settings linked to a CSI reporting settinghave the same DL BWP.

In a CSI resource setting included in CSI-ResourceConfig IE, a timedomain behavior of a CSI-RS resource may be indicated by higher layerparameter resourceType and may be configured to be aperiodic, periodic,or semi-persistent.

The number S of CSI-RS resource sets configured for periodic andsemi-persistent CSI resource settings is restricted to “1”.

A periodicity and a slot offset configured for periodic andsemi-persistent CSI resource settings are given from a numerology ofrelated DL BWP, just like being given by bwp-id.

When the UE is configured with a plurality of CSI-ResourceConfigincluding the same NZP CSI-RS resource ID, the same time domain behavioris configured for the CSI-ResourceConfig.

When the UE is configured with a plurality of CSI-ResourceConfig havingthe same CSI-IM resource ID, the same time domain behavior is configuredfor the CSI-ResourceConfig.

Then, one or more CSI resource settings for channel measurement (CM) andinterference measurement (IM) are configured through higher layersignaling.

-   -   A CSI-IM resource for interference measurement.    -   An NZP CSI-RS resource for interference measurement.    -   An NZP CSI-RS resource for channel measurement.

That is, a channel measurement resource (CMR) may be an NZP CSI-RS forCSI acquisition, and an interference measurement resource (IMR) may bean NZP CSI-RS for CSI-IM and for IM.

Herein, CSI-IM (or a ZP CSI-RS for IM) is primarily used for inter-cellinterference measurement.

In addition, an NZP CSI-RS for IM is primarily used for intra-cellinterference measurement from multi-user.

The UE may assume that a CSI-RS resource(s) and a CSI-IM/NZP CSI-RSresource(s) for interference measurement configured for one CSIreporting is “QCL-TypeD” for each resource.

Resource Setting Configuration

As described above, a resource setting may represent a resource setlist.

Regarding aperiodic CSI, each trigger state configured using higherlayer parameter “CSI-AperiodicTriggerState” is that eachCSI-ReportConfig is associated with one or multiple CSI-ReportConfiglinked to a periodic, semi-persistent, or aperiodic resource setting.

One reporting setting may be connected to three resource settings atmaximum.

-   -   When one resource setting is configured, a resource setting        (given by higher layer parameter resourcesForChannelMeasurement)        is about channel measurement for L1-RSRP computation.    -   When two resource settings are configured, the first resource        setting (given by higher layer parameter        resourcesForChannelMeasurement) is for channel measurement and        the second resource setting (given by        csi-IM-ResourcesForInterference or        nzp-CSI-RS-ResourcesForInterference) is for CSI-IM or for        interference measurement performed on an NZP CSI-RS.    -   When three resource settings are configured, the first resource        setting (given by resourcesForChannelMeasurement) is for channel        measurement, the second resource setting (given by        csi-IM-ResourcesForInterference) is for CSI-IM based        interference measurement, and the third resource setting (given        by nzp-CSI-RS-ResourcesForInterference) is for NZP CSI-RS based        interference measurement.

Regarding semi-persistent or periodic CSI, each CSI-ReportConfig islinked to a periodic or semi-persistent resource setting.

-   -   When one resource setting (given by        resourcesForChannelMeasurement) is configured, the resource        setting is about channel measurement for L1-RSRP computation.    -   When two resource settings are configured, the first resource        setting (given by resourcesForChannelMeasurement) is for channel        measurement, and the second resource setting (given by the        higher layer parameter “csi-IM-ResourcesForInterference”) is        used for interference measurement performed on CSI-IM.

CSI computation regarding CSI measurement will be described in moredetail.

If interference measurement is performed on CSI-IM, each CSI-RS resourcefor channel measurement is associated with a CSI-RS resource in acorresponding resource set by an order of CSI-RS resources and CSI-IMresources.

The number of CSI-RS resources for channel measurement is the same asthe number of CSI-IM resources.

In addition, when interference measurement is performed on an NZPCSI-RS, the UE is not expected to be configured with one or more NZPCSI-RS resources in an associated resource set within a resource settingfor channel measurement.

A UE configured with higher layer parameternzp-CSI-RS-ResourcesForInterference is not expected to be configuredwith 18 or more NZP CSI-RS ports in a NZP CSI-RS resource set.

For CSI measurement, the UE assumes the following.

-   -   Each NZP CSI-RS port configured for interference measurement        corresponds to an interference transmission layer.    -   Every interference transmission layer of NZP CSI-RS ports for        interference measurement considers an energy per resource        element (EPRE) ratio.    -   a different interference signal on a RE(s) of an NZP CSI-RS        resource for channel measurement, an NZP CSI-RS resource for        interference measurement, or a CSI-IM resource for interference        measurement.

A CSI reporting procedure will be described in more detail.

For CSI reporting, time and frequency resources available for an UE arecontrolled by a base station.

CSI may include at least one of channel quality indicator (CQI), aprecoding matrix indicator (PMI), a CSI-RS resource indicator (CRI), amSS/PBCH block resource indicator (SSBRI), a layer indicator (LI), a rankindicator (RI), or L1-RSRP.

Regarding the CQI, the PMI, the CRI, the SSBRI, the LI, the RI, and theL1-RSRP, the UE may be configured with N CSI-ReportConfig reportingsetting, M CSI-ResourceConfig resource setting, and a list of one or twotrigger states (provided by aperiodicTriggerStateList andsemiPersistentOnPUSCH-TriggerStateList) by a higher layer.

In the aperiodicTriggerStateList, each trigger state includes a channeland a list of associated CSI-ReportConfigs selectively indicative ofResource set IDs for interference.

In the semiPersistentOnPUSCH-TriggerStateList, each trigger stateincludes one associated CSI-ReportConfig.

In addition, a time domain behavior of CSI reporting supports periodic,semi-persistent, and aperiodic CSI reporting.

Hereinafter, periodic, semi-persistent, and aperiodic CSI reporting willbe described.

The periodic CSI presorting is performed on a short PUCCH and a longPUCCH.

A periodicity and a slot offset of the periodic CSI reporting may beconfigured by RRC and refer to CSI-ReportConfig IE.

Then, SP CSI reporting is performed on a short PUCCH, a long PUCCH, or aPUSCH.

In the case of SP CSI on a short/long PUCCH, a periodicity and a slotoffset are configured by RRC, and CSI reporting to an additional MAC CEis activated/deactivated

In the case of SP CSI on a PUSCH, a periodicity of SP CSI reporting isconfigured by RRC, but a slot offset thereof is not configured by RRCand SP CSI reporting is activated/deactivated by DCI (format 0_1).

The first CSI reporting timing follows a PUSCH time domain allocationvalue indicated by DCI, and subsequent CSI reporting timing follows aperiodicity which is configured by RRC.

For SP CSI reporting on a PUSCH, a separated RNTI (SP-CSI C-RNTI) isused.

DCI format 0_1 may include a CSI request field and activate/deactivate aspecific configured SP-CSI trigger state.

In addition, SP CSI reporting is activated/deactivated identically orsimilarly to a mechanism having data transmission on a SPS PUSCH.

Next, aperiodic CSI reporting is performed on a PUSCH and triggered byDCI.

In the case of AP CSI having an AP CSI-RS, an AP CSI-RS timing isconfigured by RRC.

Herein, a timing of AP CSI reporting is dynamically controlled by DCI.

A reporting method (e.g., transmitting in order of RI, WB, PMI/CQI, andSB PMI/CQI) by which CSI is divided and reported in a plurality ofreporting instances, the method which is applied for PUCCH-based CSIreporting in LTE, is not applied in NR.

Instead, NR restricts configuring specific CSI reporting on a short/longPUCCH, and a CSI omission rule is defined.

Regarding an AP CSI reporting timing, PUSCH symbol/slot location isdynamically indicated by DCI. In addition, candidate slot offsets areconfigured by RRC.

Regarding CSI reporting, a slot offset(Y) is configured for eachreporting setting.

Regarding UL-SCH, a slot offset K2 is configured separately.

Two CSI latency classes (low latency class and high latency class) aredefined in terms of CSI computation complexity.

The low latency CSI is WB CSI that includes up to 4-ports Type-Icodebook or up to 4-ports non-PMI feedback CSI.

The high latency CSI is a CSI other than the low latency CSI.

Regarding a normal UE, (Z, Z′) is defined in a unit of OFDM symbols.

Z represents the minimum CSI processing time after receiving CSItriggering DCI and before performing CSI reporting.

Z′ represents the minimum CSI processing time after receiving CSI-RSabout a channel/interference and before performing CSI reporting

Additionally, the UE reports the number of CSI which can be calculatedat the same time.

CSI Reporting Using PUSCH

FIG. 16 shows an example of information payload of PUSCH-based CSIreporting.

NZBI is a parameter representing an indication of the number of non-zerowideband amplitude coefficients for each layer in Type II PMI code book.

When DCI is decoded, a UE performs aperiodic CSI reporting using a PUSCHof a serving cell c.

The aperiodic CSI reporting performed on the PUSCH supports wideband andsub-band frequency granularity.

The aperiodic CSI reporting performed on the PUSCH supports Type I andType II CSI.

If DCI format 0_1, which activates a semi-persistent (SP) CSI triggerstate, is decoded, a UE performs SP CSI reporting on the PUSCH.

DCI format 0_1 includes a CSI request field indicative of an SP CSItrigger state to be activated or deactivated.

SP CSI reporting on the PUSCH supports Type I and Type II CSI havingwideband and sub-band frequency granularity.

A PUSCH resource and a Modulation and Coding Scheme (MCS) for SP CSIreporting are semi-persistently allocated by UL DCI.

CSI reporting for the PUSCH may be multiplexed with UL data on thePUSCH.

In addition, CSI reporting for the PUSCH may be performed without beingmultiplexed with UL data.

As illustrated in FIG. 16, regarding Type I and Type II CSI, CSIreporting on the PUSCH may include two parts (Part 1 and Part 2)illustrated in FIG. 16.

Part 1 (1610) is used to identify the number of information bits of Part2 (1620). Part 1 is entirely transmitted before Part 2.

-   -   Regarding Type I CSI feedback, Part 1 includes (when reported)        RI, (when reported) CRI, and CQI of the first codeword.

Part 2 includes a PMI, and, when RI>4, parts 2 includes a CQI.

-   -   Regarding Type II CSI feedback, Part 1 has a fixed payload size        and includes an RI, a CQI, and an indication (NZBI) indicative        of the number of non-zero wideband amplitude coefficients for        each layer of Type II CSI.

In Part 1, the RI, the CQI, and the NZBI are encoded additionally.

Part 2 includes a PMI of Type II CSI.

Part 1 and Part 2 are additionally encoded.

A Type II CSI report transmitted on the PUSCH is calculated independentof every Type II CSI reporting transmitted on PUCCH format 1, 3, or 4.

If higher layer parameter reportQuantity is set to one of “cri-RSRP” or“ssb-Index-RSRP”, a CSI feedback is composed of a single Part.

Regarding Type I and Type II CSI reporting which are configured for aPUCCH but transmitted on a PUSCH, an encoding scheme follows an encodingscheme of the PUCCH.

If CSI reporting includes two parts in the PUSCH and a CSI payload issmaller than a payload size provided by a PUSCH resource allocated forCSI reporting, the UE may omit some of Part 2 CSI.

Omission of Part 2 CSI is determined by a priority order, and Priority 0is the highest priority and 2N_(Rep) is the lowest priority.

CSI Reporting Using PUCCH

A UE is configured semi-statically by a higher layer in order to performperiodic CSI reporting on a PUCCH.

The UE may be configured by higher layers for multiple periodic CSIreports corresponding to one or more higher layer configured CSIreporting setting Indications, where the associated CSI MeasurementLinks and CSI Resource Settings are higher layer configured.

In PUCCH format 2, 3, or 4, periodic CSI reporting supports Type I CSIbased on a wide bandwidth.

Regarding SP CSI on a PUSCH, the UE performs SP CSI report on a PUCCHwhich has applied from a slot n+3N_(slot) ^(subframe,μ)+1 after HARQ-ACKcorresponding to a PDSCH carrying a selection command was transmittedfrom a slot n.

The selection command includes one or more report setting indicationswhere associated CSI resource settings are configured.

The SP CSI report supports Type I CSI on the PUCCH.

SP CSI report in PUCCH format 2 supports Type I CSI having a widebandwidth frequency granularity. SP CSI report in PUCCH format 3 or 4supports Type I sub-band CSI and Type II CSI having a wide bandwidthgranularity.

When the PUCCH carries Type I CSI having a wide bandwidth frequencygranularity, CSI payloads carried by PUCCH format 2 and PUCCH format 3or 4 are the same, irrespective of (when reported) RI, (when reported)CRI.

In PUCCH format 3 or 4, Type I CSI sub-band payload is divided into twoparts.

The first part (Part 1) includes (when reported) RI, (wen reported) CRI,and CQI of the first codeword.

The second part (Part 2) includes PMI, and, when RI>4, the second part(Part 2) includes CQI of the second codeword.

SP CSI reporting carried in PUCCH format 3 or 4 supports Type II CSIfeedback, but only Part 1 of Type II CSI feedback.

In PUCCH format 3 or 4 supporting Type II CSI feedback, CSI report maydepend on a UE capability.

Type II CSI report (only Part 1 thereof) carried in PUCCH format 3 or 4is computed independently of Type II CSI report carried in the PUSCH.

When the UE is configured with CSI reporting in PUCCH format 2, 3, or 4,each PUCCH resource is configured for each candidate UL BWP.

In the case where the UE receives active SP CSI report configuration inthe PUCCH and does not receive a deactivation command, CSI reporting isperformed when a BWP which is CSI-reported is an active BWP and,otherwise, CSI reporting is temporarily stopped. This operation applieseven in the case of SP CSI on PUCCH. Regarding PUSCH-based SP CSIreport, it is understood that corresponding CSI report is automaticallydeactivated when BWP switching occurs.

Table 10 shows an example of a PUCCH format

TABLE 10 Length in OFDM PUCCH format symbols N_(symb) ^(PUCCH) Number ofbits 0 1-2  ≤2 1 4-14 ≤2 2 1-2  >2 3 4-14 >2 4 4-14 >2

In Table 10, N_(symb) ^(PUCCH) indicates a length of PUCCH transmissionin an OFDM symbol.

In addition, depending on the length of PUCCH transmission, the PUCCHformat may be classified as a short PUCCH or a long PUCCH.

In Table 10, PUCCH format 0 and 2 may be called the short PUCCH, andPUCCH format 1, 3, and 4 may be called the long PUCCH.

Hereinafter, regarding PUCCH-based CSI reporting, short PUCCH-based CSIreporting and long PUCCH-based CSI reporting will be described in moredetail.

FIG. 17 shows an example of information payload of short PUCCH-based CSIreporting.

The short PUCCH-based CSI reporting is used only for wideband CSIreporting.

The short PUCCH-based CSI reporting has the same payload regardless ofan RI/CRI in a given slot (in order to avoid blind decoding).

A size of the information payload may be different between the maximumCSI-RS ports of a CSI-RS configured in a CSI-RS resource set.

When a payload including a PMI and a CQI are diversified to including anRI/CQI, padding bits are added to the RI/CRI/PMI/CQI before an encodingprocedure for equalizing a payload associated with different RI/CRIvalues.

In addition, the RI/CRI/PMI/CQI may be encoded with the padding bits,when necessary.

Next, long PUCCH-based CSI reporting will be described.

FIG. 18 shows an example of information payload of long PUCCH-based CSIreporting.

For wideband reporting, the long PUCCH-based CSI reporting may use thesame solution as that of the short PUCCH-based CSI reporting.

The long PUCCH-based CSI reporting has the same payload regardless of anRI/CRI.

For sub-band reporting, Two-part encoding (For Type I) is applied.

Part 1 (1810) may have a fixed payload according to the number of ports,a CSI type, RI restriction, and the like, and Part 2 (1820) may have avariety of payload sizes according to Part 1.

The CSI/RI may be first encoded to determine a payload of the PMI/CQI.

In addition, CQIi(i=1,2) corresponds to a CQI for the i-th codeword(CW).

Regarding a long PUCCH, Type II CSI reporting may carry only Part 1.

Beam Failure Detection (BFD) and Beam Failure Recover (BFR) Procedures

Next, a BFD procedure and a BFR procedure will be described.

In a Beamformed system, a Radio Link Failure (RLF) may often occur dueto a UE's rotation, movement, or beam blockage.

Accordingly, in order to prevent frequent occurrence of the RLF, RFR issupported in NR.

The BFR may be similar to a radio link failure recovery procedure andsupported when a UE knows a new candidate beams( ).

For a better understanding, (1) radio link monitoring and (2) linkrecovery procedures will be described first in brief.

Radio Link Monitoring

A DL radio link quality of a primary cell is monitored by a UE in orderto indicate an out-of-sync or in-sync state to higher layers.

The term “cell” used in the present disclosure may be a componentcarrier, a carrier, a BW, and the like.

A UE does not need to a DL radio link quality in a DL BWP other than anactive DL BWP on the primary cell.

The UE may be configured for each DL BWP of SpCell having a set ofresource indexes through a set corresponding to higher layer parameter)RadioLinkMonitoringRS for radio link monitoring by higher layerparameter failureDetectionResources.

Higher layer parameter RadioLinkMonitoringRS having a CSI-RS resourceconfiguration index (csi-RS-Index) or an SS/PBCH block index (ssb-Index)is provided to the UE.

In the case where RadioLinkMonitoringRS is not provided to the UE andinstead TCI-state for PDCCH including one or more RSs including one ormore from a CSI-RS and/or an SS/PBCH block is provided to the UE,

-   -   when active TCI-state for PDCCH include a single RS, the UE uses        the RS, provided for the active TCI-state for PDCCH, for radio        link monitoring.    -   when active TCI-state for PDCCH includes two RSs, the UE is not        expected to have one RS has QCL-TypeD and use one RS for radio        link monitoring. Herein, the UE does not expect that both the        two RSs has QCL-TypeD.    -   the UE does not use aperiodic RS for radio link monitoring.

The following Table 11 shows an example of RadioLinkMonitoringConfig IE.

The RadioLinkMonitoringConfig IE is used to configure radio linkmonitoring for detecting a beam failure and/or a cell radio linkfailure.

TABLE 11 -- ASN1START -- TAG-RADIOLINKMONITORINGCONFIG-STARTRadioLinkMonitoringConfig ::= SEQUENCE {failureDetectionResourcesToAddModList SEQUENCE(SIZE(1..maxNrofFailureDetectionResources)) OF RadioLinkMonitoringRSOPTIONAL, -- Need N failureDetectionResourcesToReleaseList SEQUENCE(SIZE(1..maxNrofFailureDetectionResources)) OF RadioLinkMonitoringRS-IdOPTIONAL,-- Need N beamFailureInstanceMaxCount ENUMERATED {n1, n2, n3,n4, n5, n6, n8, n10} OPTIONAL, -- Need S beamFailureDetectionTimerENUMERATED {pbfd1, pbfd2, pbfd3, pbfd4, pbfd5, pbfd6, pbfd8, pbfd10}OPTIONAL, -- Need R ... } RadioLinkMonitoringRS ::= SEQUENCE {radioLinkMonitoringRS-Id RadioLinkMonitoringRS-Id, purpose ENUMERATED{beamFailure, rlf, both}, detectionResource CHOICE { ssb-IndexSSB-Index, csi-RS-Index NZP-CSI-RS-ResourceId }, ... } --TAG-RADIOLINKMONITORINGCONFIG-STOP -- ASN1STOP

In Table 11, the parameter beamFailureDetectionTimer is a timer for beamfailure detection.

The parameter beamFailureDetectionTimer indicates that the UE triggers abeam failure recovery after how many beam failure events.

Value n1 corresponds to 1 beam failure instance, and value n2corresponds to 2 beam failure instances. If a network reconfigures acorresponding field, the UE resets a counter related toon-goingbeamFailureDetectionTimer and beam Failure InstanceMaxCount.

If there is no corresponding field, the UE does not trigger a beamfailure recovery.

Table 12 shows an example of BeamFailureRecoveryConfig IE.

For beam failure detection, the BeamFailureRecoveryConfig IE is used toconfigure the UE with RACH resources and candidate beams for beamfailure recovery.

TABLE 12 -- ASN1START -- TAG-BEAM-FAILURE-RECOVERY-CONFIG-STARTBeamFailureRecoveryConfig ::= SEQUENCE { rootSequenceIndex-BFR INTEGER(0..137) OPTIONAL, -- Need M rach-ConfigBFR RACH- ConfigGenericOPTIONAL, -- Need M rsrp-ThresholdSSB RSRP- Range OPTIONAL, -- Need McandidateBeamRSList SEQUENCE (SIZE(1..maxNrofCandidateBeams)) OF PRACH-ResourceDedicatedBFR OPTIONAL, -- Need M ssb-perRACH-Occasion ENUMERATED{oneEighth, oneFourth, oneHalf, one, two, four, eight, sixteen}OPTIONAL, -- Need M ra-ssb-OccasionMaskIndex INTEGER (0..15) OPTIONAL,--- Need M recoverySearchSpaceId SearchSpaceId OPTIONAL, -- Cond CF-BFRra-Prioritization RA- Prioritization OPTIONAL, -- Need RbeamFailureRecoveryTimer ENUMERATED {ms10, ms20, ms40, ms60, ms80,ms100, ms150, ms200} OPTIONAL, -- Need M ... }PRACH-ResourceDedicatedBFR ::= CHOICE { ssb BFR-SSB-Resource, csi-RSBFR-CSIRS-Resource } BFR-SSB-Resource ::= SEQUENCE { ssb SSB-Index,ra-PreambleIndex INTEGER (0..63), ... } BFR-CSIRS-Resource ::= SEQUENCE{ csi-RS, NZP-CSI-RS-ResourceId ra-OccasionList SEQUENCE(SIZE(1..maxRA-OccasionsPerCSIRS)) OF INTEGER (0..maxRA-Occasions-1)OPTIONAL, -- Need R ra-PreambleIndex INTEGER (0..63) OPTIONAL, -- Need R... } -- TAG-BEAM-FAILURE-RECOVERY-CONFIG-STOP -- ASN1STOP

In Table 12, the parameter beamFailureRecoveryTimer is a parameterindicative of a timer for beam failure recovery, and a value of theparameter is set to ms.

The parameter candidateBeamRSList is a parameter indicative of a list ofreference signals (CSI-RS and/or SSB) to identify random access (RA)parameters associated with candidate beams for recovery.

The parameter RecoverySearchSpaceId represents a search space used forBFR random access response (RAR).

If radio link quality is poorer than the threshold Qout, the physicallayer of a UE indicates the out-of-sync status for a higher layer withina radio frame whose radio link quality was measured.

If the radio link quality is better than the threshold Qin, the physicallayer of the UE indicates the in-sync status for a higher layer within aradio frame whose radio link quality was measured.

Link Recovery Procedure

A UE is provided, for a serving cell, with a set q0 of periodic CSI-RSresource configuration indexes by higher layer parameterfailureDetectionResources, and a set q1 of periodic CSI-RS resourceconfiguration indexes and/or SS/PBCH block indexes bycandidateBeamRSList for measuring a radio link quality on the servingcell.

If the UE is not provided with higher layer parameterfailureDetectionResources, the UE determines the set q0 to includeSS/PBCH block indexes and periodic CSI-RS resource configuration indexeswith same values as the RS indexes in the RS sets indicated by the TCIstates for respective control resource sets that the UE uses formonitoring PDCCH.

If a threshold Qout_LR corresponds to the default value of higher layerparameter rim InSyncOutOfSyncThreshold and to the value provided byhigher layer parameter rsrp-ThresholdSSB, respectively.

The physical layer of the UE evaluates the radio link quality accordingto the set q0 of resource configurations against the threshold Qout_LR.

For the set q0, the UE assesses the radio link quality only according toperiodic CSI-RS resource configurations or SS/PBCH blocks that are quasico-located with the DM-RS of PDCCH receptions monitored by the UE.

The UE applies a Qin_LR threshold to a L1-RSRP measurement obtained fromthe SS/PBCH block.

The UE applies the Qin_LR threshold to the L1-RSRP measurement obtainedfor a CSI-RS resource after scaling a respective CSI-RS reception powerwith a value provided by higher layer parameter powerControlOffsetSS.

The physical layer in the UE provides an indication to higher layerswhen the radio link quality for all corresponding resourceconfigurations in the set that the UE uses to assess the radio linkquality is worse than the threshold Qout_LR.

The physical layer informs the higher layers when the radio link qualityis worse than the threshold Qout_LR with a periodicity determined by themaximum between the shortest periodicity of periodic CSI-RSconfigurations or SS/PBCH blocks in the set q0 that the UE uses toassess the radio link quality and 2 msec.

Upon request from higher layers, the UE provides to the higher layersthe periodic CSI-RS configuration indexes and/or SS/PBCH block indexesfrom the set q1 and the corresponding L1-RSRP measurements that arelarger than or equal to the corresponding thresholds.

A UE may be provided with a control resource set through a link to asearch space set provided by higher layer parameterrecoverySearchSpaceId for monitoring PDCCH in the control resource set.

If the UE is provided higher layer parameter recoverySearchSpaceId, theUE does not expect to be provided another search space set formonitoring PDCCH in the control resource set associated with the searchspace set provided by recoverySearchSpaceId.

The aforementioned BFD and BFR procedure will be described again.

If beam failure is detected on a serving SSB or a CSI-RS(s), a BFRprocedure used to indicate a new SSB or CSI-RS to a serving base stationmay be configured by RRC.

The RRC configures Beam FailureRecoveryConfig for a beam failuredetection and recovery procedure.

FIG. 19 is a flowchart illustrating an example of a BFR procedure.

The BFR procedure may include (a) a step of beam failure detection(S1910), (2) a step of new beam indication (s1920), a step of BeamFailure Recovery Request (RFRQ) (S1930), and (4) a step of monitoring aresponse to the BFRQ from a base station (S1940).

Herein, for the step S1930, that is, for transmission of the BFRQ, aPRACH preamble or a PUCCH may be used.

The step S1910, that is, beam failure detection will be described inmore detail.

When block error rates (BLERs) of all serving beams are greater than athreshold, it is called a beam failure instance.

An RS set q0, which a UE will monitor, is explicitly configured by RRCor implicitly determined by a beam RS for a control channel.

An indication of the beam failure instance to higher layer is periodic,and an indication interval is determined by the shortest periodicity ofBFD RS set.

If an evaluation is lower than a beam failure instance BLER threshold,there is no indication to higher layer.

When N number of consecutive beam failure instances has occurred, a beamfailure is declared.

Herein, N is the parameter NrofBeamFailureInstance which is configuredby RRC.

1-port CSI-RS and SSB are supported for a BFD RS set.

Next, the step S1920, that is, new beam indication will be described.

A network NW may transmit configuration of one or multiple PRACHresources/sequences to a UE.

A PRACH sequence is mapped to at least one new candidate beam.

The UE selects a new beam from among candidate beams having L1-RSRPequal to or greater than a threshold configured by RRC, and transmits aPRACH via the selected beam. In this case, which beam the UE selects maybe an UE implementation issue.

Next, the steps S1930 and S1940, that is, transmitting a BFRQ andmonitoring a response to the BRFQ will be described.

A dedicated CORESET may be configured by RRC to monitor a time durationof a window and the response to the BFRQ from the base station.

The UE starts to monitor after 4 slots of PRACH transmission.

The UE assumes that the dedicated CORESET is spatial QCL with a DL RS ofa UE-identified candidate beam in the beam failure recovery request.

If the timer expires or when the number of PRACH transmission reachesthe maximum number, the UE stops the BFR procedure.

Herein, the maximum number of PRACH transmission and the timer areconfigured with RRC.

A NR system defines a method of designing a RS for fine time/frequencytracking, and a method of configuring (indicating) an RS fortime/frequency tracking in a UE.

More specifically, before RRC connection (or a RRC_connected state), theUE may perform time and/or frequency tracking with a signal for initialaccess, such as a physical broadcast channel (PBCH), a demodulationreference signal (DMRS), a primary synchronization signal (PSS), asecondary synchronization signal (SSS).

Herein, the time/frequency tracking may mean a procedure of discovering(or tracking) a time/frequency about signal transmission and reception.

The expression “A and/or B” used throughout the present disclosure maybe interpreted as the same as “including at least one of A or B”.

In addition, when the RRC connection is established (or in the RRCconnected state), an RC for much finer time/frequency tracking may beconfigured in the UE by the base station.

The RRC connected state may be expressed as an RRC connected mode.

Hereinafter, an RS used for time/frequency tracking will be referred toas a “tracking reference signal (TRS)”

To configure a TRS in the UE, two methods may be considered.

The first method is a method in which an additional RS (which isdistinguishable from other RS) called a TRS is defined and then theadditional RS is explicitly configured.

The second method is a method in which, when an RS for tracking isconfigured using (some of) CSI-RS configurations, the UE enhancesprediction of time/frequency tracking by itself.

That is, the first method may be a method of explicitly configuring aTRS, and the second method may be a method of implicitly configuring aTRS.

The TRS defined in NR is identical to a cell-specific RS (CRS) definedin LTE since the both are about a time/frequency tracking function, butit is different from the CRS in LTE since the TRS is notcell-specifically transmitted.

Hereinafter, a TRS designing method and a TRS configuring method,proposed by the present disclosure, will be described in detail.

The base station may explicitly or implicitly configure a CSI-RS havingthe following properties ((1) to (4)) for a time/frequency tracking.

(1) Single or multiple 1-port CSI-RS resources

The 1-port CSI-RS resources may be periodic and QCL with a specificsignal.

A CSI-RS resource indicates a transmission (or reception) pattern of aCSI-RS, includes at least one RE(s), and relates to an antenna port, acode division multiplexing (CDM) scheme, and the like.

The multiple 1-port CSI-RS resources have the same periodicity and aretransmitted from the same slot or in consecutive slots.

For example, slot offsets between the multiple CSI-RS resources may beset to 0, 1, or 2.

If the slot offsets between the multiple CSI-RS resources are the same,a symbol location of each CSI-RS resource may be different in a slot,and the symbol location may be non-consecutive, that is, symbollocations of different CSI-RS resources may have a symbol interval equalto or greater than a predetermined value.

That is, the UE does not expect that a CSI-RS (resource) exists inconsecutive symbols.

Alternatively, if the CSI-RS exists in consecutive symbols, thecorresponding CSI-RS may be defined as being used for a purpose (e.g.,beam management) other than the TRS purpose.

Additionally, a QCL relationship between the multiple CSI-RS resourcesmay be assumed (or indicated).

(2) A property of a specific RE pattern(s) may be given.

No code division multiplexing (CDM) may be defined. That is, a TRS or aCSI-RS for TRS may occupy just 1 resource element (RE) on the time andfrequency axes.

In addition, a frequency domain density may be equal to or greater than1 RE/RB/port.

In addition, a time domain density may be equal to or greater than 1RE/slot/port.

If the time domain density is greater than 1, it may be limited to thecase where symbols in which a CSI-RS exists are non-consecutive. Thatis, a pattern of non-consecutive symbols may be excluded.

(3) TRS configuration may be configured (or applied) only when it isconfigured as a CSI-RS resource type used for beam management (BM).

That is, even in the case of a 1-port resource, a CSI-RS type for CSIacquisition may be restricted not to be used for a TRS purpose.

(4) A CSI-RS for TRS is periodically or semi-persistently transmittedand has a property that a time domain measurement restriction becomes“OFF”.

In a method of configuring a TRS by aggregating multiple 1-port CSI-RSresources among the aforementioned methods, it is assumed (or indicated)that the CSI-RS resources are all QCL.

This means that the CSI-RS resources are QCL even in terms of a spatialRx parameter since the multiple CSI-RS resources are transmitted via thesame beam along with a channel's long term property such as Doppler,Delay, Gain, etc.

In addition, it may be more desirable to guarantee that CSI-RSs whichconfigure a TRS have the same short term channel property (e.g., phaseoffset, and delay profile).

Alternatively, it may be more desirable to allow corresponding CSI-RSresources or ports to estimate (or infer) each other's channel from aradio channel experienced by other resources (or ports).

For reference, an antenna port is defined such that a channel over whicha symbol on one antenna port is transmitted can be inferred from anotherchannel over which a symbol on another antenna port is transmitted.

Accordingly, it may be more desirable that the multiple 1-port CSI-RSresources are assumed (or indicated) to be in a more strong associationrelationship stronger than QCL.

As an example of the association relationship, the same antenna port maybe assumed (or indicted), or a new term indicating that antennaports/resources have the same short-term channel property or that theantenna ports/resources can be inferred with the same channel may bedefined.

In doing so, a method of assuming (or indicating) a correspondingrelationship (GCL or IAP) between the CSI-RS resources (or ports) may bedefined additionally.

GCL (genuine co-location): a (short and long) property of a channel overwhich a symbol on one antenna port is transmitted can be inferred from achannel over which a symbol on another antenna port is transmitted, thetwo antenna ports are defined as being GCL with each other.

IAP (identical antenna port): in the case where a channel over which asymbol on one antenna port is transmitted can be inferred from a channelover which a symbol on another antenna port is transmitted, the twoantenna ports are defined as being identical.

Alternatively, in addition to the six parameters (delay spread, Dopplerspread, Doppler shift, average gain, average delay, and spatial Rxparameters) in the previously defined relationship QCL, it is possibleto add new (short-term) channel parameters (e.g., delay profile, Dopplerprofile, phase offset, instantaneous gain, etc.) and then assume (orindicate) a QCL relationship (even) with the new channel parametersbetween the corresponding CSI-RS (or ports).

In another embodiment, the following methods may be additionally definedregarding TRS configuration.

(1) (CSI-RS resources having the above properties (1) to (4) in) someresource settings out of resource settings defined for CSI acquisitionand beam management may be configured for TRS.

The resource settings for TRS may be distinguished by the followingproperties.

-   -   a resource setting without linkage to any reporting settings, or    -   a resource setting with linkage to a NULL reporting setting, or        wherein the null reporting setting may mean a report setting        indicating that an UE does not need to report any information to        a gNB,    -   a resource setting with linkage to a reporting setting for TRS        quality feedback (e.g., L1-RSRP).

With the above properties unlike other resource settings, RSs for TRSare used to enhance channel estimation performance of a UE and do notneeds to be used for reporting of the UE.

However, exceptionally, RSRP reporting may be configured in a reportingsetting to allow a base station to confirm a TRS quality.

Accordingly, when the base station (periodically) transmits a TRSthrough a resource setting in which a report setting is not configured(and/or resource setting in which TRS quality reporting is configured),the UE may perform time/frequency tracking via a corresponding resource.

The resource setting, in which reporting is excluded (or CSI-RS qualityreporting is configured), may be used not just for TRS but also for Rxbeam selection/refinement.

That is, when the base station repeatedly transmits a CSI-RS via thesame beam (to different symbols), the UE may perform Rx beamselection/refinement (e.g., P-3 purpose) while changing a Rx beam.

In this case, a procedure in which the UE reports beam qualityinformation (L1-RSRP or CQI) of a (refined) Rx beam to the base stationmay be added.

The P-3 operation and the fine time/frequency tracking operation may bethe same as the above description in terms of RS transmission setting ofthe base station.

However, in the former case, since the UE receives signals whilechanging an Rx beam, tracking may not be possible but beam selection maybe possible.

In addition, in the latter case, the UE may enhance tracking performancewhile receiving the CSI-RS via the same beam but may not be able toperform beam selection.

To distinguish the above two purposes, the following methods may bedefined additionally.

-   -   The base station may add, in a resource setting, an indicator        indicative of P-3 purpose or TRS purpose.    -   It may be implicitly distinguished such that a CSI-RS is        transmitted to consecutive symbols for P-3 purpose, and a CSI-RS        resource is transmitted to non-consecutive symbols or at a        predetermined symbol interval for TRS purpose.    -   Since the UE receives a CSI-RS symbol(s) for P-3 purpose while        changing a (Rx) beam, the CSI-RS symbol is not allowed to be        frequency domain multiplexing (FDM) with a different signal (or        channel, for example, a PDSCH) and received at the same time.

However, for TRS purpose, the UE does not change a (Rx) beam, so theCSI-RS symbol is FDM with a different signal (or channel) and receivedat the same time, and, this property makes it possible to implicitlydistinguish TRS purpose.

If a CSI-RS and a PDSCH are multiplexed, the property may be indicatedthrough whether the corresponding CSI-RS symbols are PDSCH rate matched.

For reference, P-3 purpose may be achieved using a single symbol CSI-RSwhich is transmitted in a comb X form.

It is because repeated signals in the form of a sub-symbol are generatedX number of times in a single symbol section.

-   -   P-3 purpose and TRS purpose may be implicitly distinguished such        that a CSI-RS is transmitted aperiodically for P-3 purpose and a        CSI-RS is transmitted periodically or semi-persistently for TRS        purpose.

In addition, in order to remove ambiguity regarding distinguishing theP-3 purpose and the TRS purpose, CSI-RS resources for TRS may beconfigured separately from resource settings included in a CSI/beammanagement framework or TRS may be defined as an RS distinguishable froma CSI-RS (that is, defined with a different antenna port).

Herein, TRS resources (or ports) respectively indicate QCL linkage withresource settings configured in a CSI/beam management framework or withNZP resources on the basis of a resource set unit.

That is, resources for fine time/frequency tracking per CSI-RS beam(group) may be configured through QCL linkage.

The QCL linkage may be a unit of a CSI-RS resource (or port/beam)corresponding to a CSI-RS beam.

In addition, QCL linkage with a TRS may be indicated (or configured) onthe basis of a synchronization signal (SS) block (group), which is atransmission unit of a synchronization signal, through beam forming.

In addition, if multiple TRS resources are configured with RRC for finetime/frequency tracking of each beam and/or transmission reception point(TRP), measurement, reception, activation, monitoring, and rate matchingof only a specific TRS resource(s) (corresponding to a serving beam(s))may be indicated in order to adjust resource overhead.

Such an indication may be enabled implicitly by spatial QCL indicationinformation between a CSI-RS resource (or an SS block) and a PDCCH DMRSfor PDCCH reception beam configuration.

That is, when QCL information between a specific CSI-RS resource (or SSblock) and a PDCCH DMRS is indicated (by MAC CE) to receive a PDCCH,reception, measurement, activation, and rate-matching may be performedonly on a TRS resource which is predetermined to be in QCL linkage tothe corresponding CSI-RS resource or (an SS block).

When multiple PDCCH Rx beams are configured, TRS resources connected toall or some (e.g., only primary PDCCH) of corresponding CSI-RS resources(or SS blocks) may be subject to reception, measurement, activation,monitoring, and rate-matching.

Alternatively, a TRS resource(s) may be configured to be subject toreception, measurement, activation, and rate-matching based on a PDSCHbeam.

In this case, the PDSCH beam may be dynamically changed by DCI.Accordingly, TRS resources linked to multiple CSI-RS (or SS block)beams/resources possibly to be changed may be (all) activated,monitored, and rate matched.

The candidate CSI-RS (or SS block) beams/resources may be (i) determinedby (multiple) preferred beam index(s) (e.g., CRI or CRI+port selectionPMI) reported by a UE, or (ii) directly/indirectly indicated by a basestation.

In the case of (ii), a TRS resource(s) for receiving, measuring,activating, monitoring, and rate-matching of a TRS may be directlyindicated, or a CSI-RS resource(s) or an SS block(s) which is in QCLlinkage indirectly to the TRS resource(s) may be indicated.

If the TRS resource(s) is indirectly indicated, the corresponding CSI-RS(or SS block) may be indicated as TRP and/or beam set information thatcan transmit a PDSCH.

This may match with CSI-RS (or SS block) resource information itemswhich can be indicated with a PDSCH beam.

For example, if ten CSI-RS resources (beams) are configured with RRC,four out of the ten CSI-RS resources may be selected and indicated asMAC CEs (according to beam-related feedback information of the UE), andthen one out of the four CSI-RS resources may be dynamically indicatedby 2-bit DCI to be (spatial) QCL with a PDSCH DMRS.

In this case, the four CSI-RS resources indicated as MAC CEs are beamcandidates capable of transmitting a PDSCH, and therefore, TRSreception/measurement/activation/monitoring/rate matching may beperformed on only TRS resources which are QCL with the CSI-RS resourcesindicated as the MAC CEs, while TRSreception/measurement/activation/monitoring/rate matching may not beperformed on TRS resources which are QCL with other six CSI-RS resources(beams).

That is, only a 1-port and high-density CSI-RS, which is QCL withresources indicated by an MAC CE, may be (automatically) activated inorder to indicate a spatial QCL between a PDSCH DMRS and the CSI-RS.

In this case, a transmission cycle, a slot offset, and the like of thecorresponding TRS (or the 1-port and high-density CSI-RS) may beconfigured with RRC.

The rate matching is an operation of performing RE mapping on a PDSCH ora PUSCH, which is a data transmission channel, except a correspondingTRS RE(s), so as to control interference from the corresponding TRS on adata channel and interference from the data channel on the correspondingTRS.

In terms of rate matching, it is possible to perform TRS rate matchingnot just on a PDCCH/PDSCH beam but also on neighboring beams of thecorresponding beam in order to control interference.

A beam ID set or a TRS set subject to rate matching according to anindicated (or configured) PDCCH/PDSCH beam ID (e.g., a CSI-RS resourceor SS block ID which is in spatial QCL with a PDCCH/PDSCH DMRS) may beconfigured by a network (with an RRC message) or may be predefinedaccording a certain rule (via table, formula, etc.).

For example, when CRI (or SS block ID)=X, wherein the CRI is indicated(or reported by a UE) as a PDCCH/PDSCH (candidate) beam, CSI-RS resourceindexes (or SS block IDs) subject to TRS rate matching may be configuredor may be predefined by a rule.

Herein, TRS resources which are QCL with corresponding CSI-RS resources(or SS blocks) may be subject to rate matching.

In another example, a resource(s) subject to rate matching amongmultiple TRS resources configured by RRC may be dynamically and directlyor indirectly indicated by an MAC CE and/or DCI.

A method for indirect indication may be, when PDSCH candidate CSI-RSbeams to be finally indicated by DCI are updated by a MAC CE, performingrate matching of TRS resources which are QCL with the updated PDSCHcandidate beams and neighboring beams (predefined according to aspecific rule or RRC configuration)

In the above, methods for explicitly or implicitly distinguishing andconfiguring a CSI-RS resource for TRS and a CSI-RS resource for beammanagement/CSI acquisition have been described.

Herein, a specific CSI-RS resource(s) may be used for multiple purposes.

For example, when a UE is configured with a CSI-RS resource havingproperties of a periodicity, 1 port, a high frequency density, andmulti-symbols according to resource setting(s), the UE may use thecorresponding resource for (Rx) beam selection/correction or (or at thesame time) for time/frequency tracking.

In this case, the above descriptions may be interpreted as a resourceadditionally for TRS, not as a TRS-dedicated resource.

It may be interpreted as the aforementioned CSI-RS having propertiessuch as a 1 port, a short periodicity, multi-symbols in a slot, andfrequency density>1.

In the above, a method in which a base station configures a TRS to a UEhas been described in detail.

Hereinafter, a method in which the UE reports information (helpfulinformation) to help the base station to determine a TRS density/patternwill be further described.

AS an example of the helpful information, a UE receiver capabilityand/or channel estimator capability information (e.g. whether or not 2Dinterpolation is performed, accuracy, etc.) may be considered.

The helpful information may be expressed as control information,auxiliary information, etc.

In the case of estimation of a UE's channel, if the UE performs 2Dinterpolation with a time domain and a frequency domain, it is necessaryto transmit a TRS to multiple symbols in a single slot for Dopplerestimation: however, if not, it is enough to transmit a TRS to a singlesymbol.

AS an example of the helpful information, time/frequency TRS density (orpattern) information may be considered.

The time density information may be substituted by a degree of Dopplerspread or information on a moving speed of the UE.

In addition, the frequency density information may be substituted by adegree of delay spread.

When a TRS is configured by aggregating multiple CSI-RS resources (in asingle or consecutive slots), it is possible to report required time(and/or frequency) density and pattern information by transmittinginformation on a preferred CSI-RS resource (set) to the base station.

For example, if a CSI-RS resource 1 (6^(th) symbol) and CSI-RS resource2 (12^(th) symbol) are indicated for TRS purpose, the UE may select arequired resource (combination) from among {1}, {2}, and {1,2} andreport the selected resource (combination) to the base station.

Herein, different CSI-RS resources may have different time/frequencydensity values, and selecting one (or multiple) resource from thedifferent CSI-RS resources may bring about the same effect as reportinga required density.

In addition, the helpful information may consider TRS bandwidthinformation, required TRS transmission periodicity information, etc.

In addition, the helpful information may be configured based on anarbitrary combination of the above-described examples of the helpfulinformation.

The helpful information may be information which is reported (ortransmitted), just like UE capability signaling, by UE upon accessing anetwork, or may be on-demand information which is requested after RRCconnection establishment.

In the latter case (UE capability), if BW, time/frequency density,periodicity, etc. of a (default) TRS preset by the base station are notenough for the UE or if there is no preset TRS, the UE may transmit a ULsignal to the base station so as to request TRS configuration(transmission) and/or request density, periodicity, BW adjustment, etc.

Herein, the UL signal may be transmitted through a PRACH or a UL channel(e.g., a specific format of FDMed/CDMed channel, PUCCH having the PRACH(hereinafter, referred to as “BRCH” for convenience of explanation)) forbeam failure recovery.

In this case, the following three procedures are all allowed.

(Procedure 1): When a UE receives configuration of a PUSCH resourcealong with a response from a base station after transmitting a UL signalthrough a PRACH/BRACH, the UE may transmit a TRS configuration requestand/or density, periodicity, BW adjustment information to the basestation through the configured PUSCH resource.

(Procedure 2): An additional resource for the above purpose may bedefined in the PRACH/BRCH (this resource may be CDM, FDM, and/or TDMwith a PRACH/BRCH resource or may be distinguishable by a messagefield), and a base station may receive a TRS configuration requestand/or density, periodicity, BW adjustment request information via a ULsignal transmitted by a UE via the above resource.

(Procedure 3): An additional resource for the above purpose may bedefined in the PRACH/BRCH (this resource may be CDM, FDM, and/or TDMwith a PRACH/BRCH resource or may be distinguishable by a messagefield), and a base station may receive a TRS configuration request via asignal transmitted by the UE via the above resource and allocate a PUSCHresource which transmits detailed request information.

The UE may transmit required density, periodicity, BW (adjustment)information via the allocated PUSCH resource.

In another example, the UL signal may be defined as being transmittedtogether or separately in the form of a power headroom report (PHR)and/or a specific UL signal such as a buffer status report.

In addition, a reporting triggering condition of the information may bedefined additionally.

FIG. 20 is a flowchart illustrating time/frequency tracking operation ofa base station which is proposed in the present disclosure.

First, the base station configures control information indicating thatan antenna port for all CSI-RS resources included in a CSI-RS resourceset is same (S2010).

Herein, the CSI-RS resource set may be used for tracking at least one oftime or frequency.

That is, a CSI-RS for tracking may be called “tracking RS (TRS)”.

In addition, the base station transmits the configured controlinformation to a UE (S2020).

The base station transmits the CSI-RS to the UE through all the CSI-RSresources (S2030).

In particular, the antenna port may be 1-port, and the UE may be in anRRC connected state.

All the CSI-RS resources may be configured with the same periodicity.

All the CSI-RS resources may be configured in a single slot or multipleslots, and the multiple slots may be consecutive slots.

If all the CSI-RS resources are configured in the single slot, symbollocations of the CSI-RS resources may be different.

A frequency domain density for each of all the CSI-RS resources may begreater than 1.

The CSI-RS resource set is not configured for both of tracking and beammanagement.

The CSI-RS resources used for tracking may be configured to be QCL witha CSI-RS resource used for CSI acquisition, with a CSI-RS resource usedfor beam management, or with a SSB (SS/PBCH block).

The CSI-RS resources may be periodic CSI-RS resources.

In addition, a time domain measurement restriction for the CSI-RSresources may be set to “OFF”.

In addition, linkage between a CSI-RS resource set of a periodic CSI-RSand a report setting is not set.

In addition, linkage between the CSI-RS resource set and a specificreport setting and linkage may be set, and the specific report settingmay be a null reporting setting.

Additionally, the base station may receive information about a timedomain density of the CSI-RS resources from the UE.

In this case, the time domain may be the same slot or consecutive slots.

FIG. 21 is a flowchart illustrating time/frequency tracking operation ofa UE which is proposed in the present disclosure.

First, the UE may receive, from the base station, control informationindicating that an antenna port for all CSI-RS resources included in aCSI-RS resource set is same (S2110).

Herein, the CSI-RS resource set may be used for tracking at least one oftime or frequency.

The UE receives a CSI-RS from the base station through all the CSI-RSresources (S2120).

Herein, the same antenna port may be configured for all the CSI-RSresources.

In particular, the antenna port may be 1-port, and the UE may be in anRRC connected state.

The same periodicity may be configured for all the CSI-RS resources.

All the CSI-RS resources may be configured in a single slot or multipleslots, and the multiple slots may be consecutive slots.

When all the CSI-RS resources are configured in the single slot, symbollocations for the CSI-RS resources may be different.

A frequency domain density for each of all the CSI-RS resource may begreater than 1.

The CSI-RS resource set is not configured for both of tracking and beammanagement.

In addition, the CSI-RS resources used for the tracking may beconfigured to be QCL with the CSI-RS resources used for tracking and theCSI-RS resources used for beam management.

The CSI-RS may be a periodic CSI-RS.

In addition, the UE performs tracking on at least one of time orfrequency based on the received CSI-RS (S2130).

General Device to which the Present Disclosure May be Applied

FIG. 22 is a block diagram of a wireless communication device to whichmethods proposed in the present disclosure may be applied.

Referring to FIG. 22, a wireless communication system includes a basestation 2210 and multiple UEs 2220 located within a region of the basestation.

Each of the base station and the UE may be represented as a wirelessdevice.

The base station includes a processor 2211, a memory 2212, and a radiofrequency (RF) module 1613. The processor 2211 implements functions,procedures, and/or methods proposed in FIGS. 1 to 21. Layers of awireless interface protocol may be implemented by the processor. Thememory is connected to the processor and stores various types ofinformation required to drive the processor. The RF module is connectedto the processor to transmit and/or receive a wireless signal.

The UE includes a processor 221, a memory 2222, and an RF module 2223.

The processor implements functions, procedures, and/or methods proposedin FIGS. 1 to 21. Layers of a wireless interface protocol may beimplemented by the processor. The memory is connected to the processorand stores various types of information required to drive the processor.The RF module is connected to the processor to transmit and/or receive awireless signal.

The memory 2212 or 2222 may be inside or outside the processor 2211 or2221, and may be connected to a processor through various well-knownmeans.

In addition, the base station and/or UE may have a single antenna ormultiple antennas.

The antenna 2214 or 2224 has a function of transmitting and receiving awireless signal.

FIG. 23 is a block diagram of a communication device according to anembodiment of the present disclosure.

Particularly, FIG. 23 is a diagram illustrating a UE shown in FIG. 22 inmore detail.

Referring to FIG. 23, the UE includes a processor (or digital signalprocessor; DSP) 2310, an RF module (RF unit) 2335, a power managementmodule 2305, an antenna 2340, a battery 2255, a display 2315, a keypad2320, a memory 2330, a Subscriber Identification Module (SIM) card 2325(which may be optional), a speaker 2345 and a microphone 2350. The UEmay include a single antenna or multiple antennas.

The processor 2310 may be configured to implement the functions,procedures and/or methods proposed by the present disclosure asdescribed in FIGS. 1 to 21. Layers of a wireless interface protocol maybe implemented by the processor 2310.

The memory 2330 is connected to the processor 2310 and storesinformation related to operations of the processor 2310. The memory 2330may be located inside or outside the processor and may be connected tothe processors through various well-known means.

A user enters instructional information, such as a telephone number, forexample, by pushing the buttons of a keypad 2320 or by voice activationusing the microphone 2350. The processor receives and processes theinstructional information to perform the appropriate function, such asto dial the telephone number. Operational data may be retrieved from theSIM card 2325 or the memory 2330 to perform the function. Furthermore,the processor may display the instructional and operational informationon the display 2315 for the user's reference and convenience.

The RF module 2335 is connected to the processor, transmits and/orreceives an RF signal. The processor forwards instructional informationto the RF module, to initiate communication, for example, transmitsradio signals comprising voice communication data. The RF moduleincludes a receiver and a transmitter to receive and transmit radiosignals. An antenna 2340 facilitates the transmission and reception ofradio signals. Upon receiving radio signals, the RF module may forwardand convert the signals to baseband frequency for processing by theprocessor. The processed signals may be transformed into audible orreadable information outputted via the speaker 2345.

FIG. 24 is a diagram illustrating an example of an RF module of awireless communication apparatus to which the method proposed in thepresent disclosure may be applied.

Particularly, FIG. 24 shows an example of an RF module that may beimplemented in Frequency Division Duplex (FDD) system.

First, in a transmit path, the processor described in FIGS. 22 and 23processes data to be transmitted and provides an analog output signal totransmitter 2410.

Within the transmitter 2410, the analog output signal is filtered by alow pass filter (LPF) 2411 to remove undesired images caused by priordigital-to-analog conversion (ADC), upconverted from baseband to RF byan upconverter (Mixer) 2412, and amplified by a variable gain amplifier(VGA) 2413. The amplified signal is filtered by a filter 2414, furtheramplified by a power amplifier (PA) 2415, routed through duplexer(s)2450/antenna switch(s) 2460, and transmitted via an antenna 2470.

In addition, in the receive path, an antenna 2470 receives signals fromexterior and provides the received signals, which is routed throughantenna switch(s) 2460/duplexer(s) 2450 and provided to the receiver2420.

Within the receiver 2420, the received signal is amplified by a lownoise amplifier (LNA) 2423, filtered by a band pass filter 2424, anddownconverted from RF to baseband by a downconverter (Mixer) 2425.

The downconverted signal is filtered by a low pass filter (LPF) 2426,and amplified by a VGA 2427 to obtain an analog input signal, which isprovided to the processor described in FIG. 22 and FIG. 23.

Further, a local oscillator (LO) generator 2440 generates and providestransmission and reception LO signals to upconverter 2412 anddownconverter 2425, respectively.

In addition, a phase locked loop (PLL) 2430 may receive controlinformation from the processor and provide control signals to LOgenerator 2440 to generate the transmission and reception LO signals atthe proper frequencies.

The circuits shown in FIG. 24 may be arranged differently from theconfiguration shown in FIG. 24.

FIG. 25 is a diagram illustrating another example of an RF module of awireless communication apparatus to which the method proposed in thepresent disclosure may be applied.

Particularly, FIG. 25 shows an example of an RF module that may beimplemented in Time Division Duplex (TDD) system.

The transmitter 2510 and the receiver 2520 of the RF module in the TDDsystem are the same as the structures of the transmitter and thereceiver of the RF module in the FDD system.

Hereinafter, only the structure of the RF module of the TDD system isdescribed, which is different from the RF module of the FDD system, andthe same structure is referred to the description of FIG. 24.

The signal amplified by a power amplifier (PA) 2515 of a transmitter isrouted through a band select switch 2550, a band pass filter (BPF) 2560and an antenna switch(s) 2570, and transmitted via an antenna 2580.

Further, in the receive path, the antenna 2580 receives signals fromexterior and provides the received signals, which is routed through theantenna switch(s) 2570, the band pass filter (BPF) 2560, and the bandselect switch 2550, and provided to the receiver 2520.

The aforementioned embodiments are achieved by combination of structuralelements and features of the present disclosure in a predeterminedmanner. Each of the structural elements or features should be consideredselectively unless specified separately. Each of the structural elementsor features may be carried out without being combined with otherstructural elements or features. In addition, some structural elementsand/or features may be combined with one another to constitute theembodiments of the present disclosure. The order of operations describedin the embodiments of the present disclosure may be changed. Somestructural elements or features of one embodiment may be included inanother embodiment, or may be replaced with corresponding structuralelements or features of another embodiment. Moreover, it is apparentthat some claims referring to specific claims may be combined withanother claims referring to the other claims other than the specificclaims to constitute the embodiment or add new claims by means ofamendment after the application is filed.

The embodiments of the present disclosure may be achieved by variousmeans, for example, hardware, firmware, software, or a combinationthereof. In a hardware configuration, the methods according to theembodiments of the present disclosure may be achieved by one or moreASICs (Application Specific Integrated Circuits), DSPs (Digital SignalProcessors), DSPDs (Digital Signal Processing Devices), PLDs(Programmable Logic Devices), FPGAs (Field Programmable Gate Arrays),processors, controllers, microcontrollers, microprocessors, etc.

In a firmware or software configuration, the embodiments of the presentdisclosure may be implemented in the form of a module, a procedure, afunction, etc. Software code may be stored in the memory and executed bythe processor. The memory may be located at the interior or exterior ofthe processor and may transmit data to and receive data from theprocessor via various known means.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present disclosurewithout departing from the spirit or scope of the inventions. Thus, itis intended that the present disclosure covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

INDUSTRIAL APPLICABILITY

A method of mapping a reference signal in the wireless communicationsystem of the present invention has been described with reference to anexample applied to a 3GPP LTE/LTE-A system or a 5G system (New RATsystem), it is also applicable to various wireless communicationsystems.

The invention claimed is:
 1. A method of transmitting, by a basestation, a channel state information (CSI)-reference signal (RS) in awireless communication system, the method comprising: configuringcontrol information for a plurality of CSI-RS resources, with thecontrol information indicating that an antenna port for the plurality ofCSI-RS resources configured for tracking at least one of a time or afrequency is the same; transmitting, to a user equipment (UE), thecontrol information; and transmitting, to the UE, the CSI-RS throughsame antenna port on the plurality of CSI-RS resources based on thecontrol information, wherein the plurality of CSI-RS resources areconfigured in a single slot and located at different symbol locations inthe single slot, and only one of the plurality of CSI-RS resources islocated at a single symbol in the single slot, wherein different symbollocations of the plurality of CSI-RS resources in the single slot arenot contiguous, and wherein a time domain measurement restrictionrelated to the plurality of CSI-RS resources is not configured.
 2. Themethod of claim 1, wherein the UE is in a radio resource control (RRC)connected state.
 3. The method of claim 1, wherein code divisionmultiplexing (CDM) is not applied to the plurality of CSI-RS resources.4. The method of claim 1, wherein a frequency domain density of each ofthe plurality of CSI-RS resources is greater than
 1. 5. The method ofclaim 1, wherein a first CSI-RS resource, among the plurality of CSI-RSresources that are used for the tracking is quasi co-located (QCL) with(i) a second CSI-RS resource that is used for CSI acquisition, (ii) athird CSI-RS resource that is used for beam management, or (iii) ansynchronization signal/physical broadcast channel block (SSB).
 6. Themethod of claim 1, wherein a linkage between the plurality of CSI-RSresources and a specific report setting is set.
 7. The method of claim6, wherein the specific report setting is null report setting.
 8. Themethod of claim 1, further comprising: receiving, from the UE,information related to a time-domain density of the CSI-RS resources. 9.A method of receiving, by a user equipment (UE), a channel stateinformation (CSI)-reference signal (RS) in a wireless communicationsystem, the method comprising: receiving, from a base station,configuration information for a plurality of CSI-RS resources, whereinthe configuration information comprises control information indicatingthat an antenna port for the plurality of CSI-RS resources configuredfor tracking at least one of a time or a frequency is the same;receiving, from the base station, the CSI-RS through same antenna porton the plurality of CSI-RS resources based on the control information;and tracking at least one of the time or the frequency based on theCSI-RS, wherein the plurality of CSI-RS resources are configured in asingle slot and located at different symbol locations in the singleslot, and only one of the plurality of CSI-RS resources is located at asingle symbol in the single slot, wherein different symbol locations ofthe plurality of CSI-RS resources in the single slot are not contiguous,and wherein a time domain measurement restriction related to theplurality of CSI-RS resources is not configured.
 10. A base stationconfigured to transmit a channel state information (CSI)-referencesignal (RS) in a wireless communication system, the base stationcomprising: a transmitter configured to transmit a wireless signal; areceiver configured to receive a wireless signal; at least oneprocessor; and at least one computer memory operably connectable to theat least one processor and storing instructions that, when executed,cause the at least one processor perform operations comprising:configuring control information for a plurality of CSI-RS resources,with the control information indicating that an antenna port for theplurality of CSI-RS resources configured for tracking at least one of atime or a frequency is the same; transmitting, to a user equipment (UE),the control information; and transmitting, to the UE, the CSI-RS throughsame antenna port on the plurality of CSI-RS resources based on thecontrol information, wherein the plurality of CSI-RS resources areconfigured in a single slot and located at different symbol locations inthe single slot, and only one of the plurality of CSI-RS resources islocated at a single symbol in the single slot, wherein different symbollocations of the plurality of CSI-RS resources in the single slot arenot contiguous, and wherein a time domain measurement restrictionrelated to the plurality of CSI-RS resources is not configured.
 11. Thebase station of claim 10, wherein the UE is in a radio resource control(RRC) connected state.
 12. The base station of claim 10, wherein codedivision multiplexing (CDM) is not applied to the plurality of CSI-RSresources.
 13. The base station of claim 10, wherein a frequency domaindensity of each of the plurality of CSI-RS resources is greater than 1.14. The base station of claim 10, wherein a first CSI-RS resource, amongthe plurality of CSI-RS resources that are used for the tracking isquasi co-located (QCL) with (i) a second CSI-RS resource that is usedfor CSI acquisition, (ii) a third CSI-RS resource that is used for beammanagement, or (iii) an synchronization signal/physical broadcastchannel block (SSB).
 15. The base station of claim 10, wherein a linkagebetween the plurality of CSI-RS resources and a specific report settingis set.
 16. The base station of claim 15, wherein the specific reportsetting is null report setting.
 17. The base station of claim 10,wherein the operations further comprise: receiving, from the UE,information related to a time-domain density of the CSI-RS resources.18. The method of claim 1, wherein the plurality of CSI-RS resources arenot configured both for the tracking and for reporting layer1(L1)-reference signal received power (RSRP).
 19. A terminal configuredto receive a channel state information (CSI)-reference signal (RS) in awireless communication system, the terminal comprising: a transmitterconfigured to transmit a wireless signal; a receiver configured toreceive a wireless signal; at least one processor; and at least onecomputer memory operably connectable to the at least one processor andstoring instructions that, when executed, cause the at least oneprocessor perform operations comprising: receiving, from a base station,configuration information for a plurality of CSI-RS resources, whereinthe configuration information comprises control information indicatingthat an antenna port for the plurality of CSI-RS resources configuredfor tracking at least one of a time or a frequency is the same;receiving, from the base station, the CSI-RS through same antenna porton the plurality of CSI-RS resources based on the control information;and tracking at least one of the time or the frequency based on theCSI-RS, wherein the plurality of CSI-RS resources are configured in asingle slot and located at different symbol locations in the singleslot, and only one of the plurality of CSI-RS resources is located at asingle symbol in the single slot, wherein different symbol locations ofthe plurality of CSI-RS resources in the single slot are not contiguous,and wherein a time domain measurement restriction related to theplurality of CSI-RS resources is not configured.